Vegan Blueberry Hazelnut Crumble Bars

 reading time: 8 min

This recipe was originally inspired by Sarah's Blackberry Hazelnut Crumble Bars which look just scrumptious! Since it's a little too early for harvesting a larger amount of blackberries, and we still got a bucket load of blueberries from our blueberry picking last month, I decided to make these cuties for our little Lughnasadh celebration with my parents – this harvest festival is all about the first fruits of the season, such as blueberries and redcurrants, as well as potatoes, corn and bread / grains.

he great thing about these crumble bars is that blueberries are in season right now, meaning they are cheap and easy to get in stores (or on a plantation or in nature, of course). Hazelnuts are not quite in season yet, but I still wanted to include a little foraging guide for them, as they are going to be ripe soon. The tree and nut husks are very easy to identify, so collecting the nuts is considered very safe for someone new to foraging.

These crumble bars are made with wholesome ingredients and are perfect for dessert or as a semi-healthy snack! Like a granola bar, but make it crumb cake.

Where and How to Harvest Hazelnuts

Hazelnut (Corylus avellana) is a hardy deciduous shrub or tree, also known as common hazel, European hazel, or cobnut. It is native to many parts of the temperate Northern hemisphere, and is often found in hedgerows and deciduous woodland. Hazelnuts produce nuts when they are around 4 years of age but don't really become productive until they are closer to 7 years of age.

Hazelnuts prefer full sun or light shade, and they like to grow in light, well-drained, loamy soil which is kept moist. They tend to grow to heights of around 10 to 15 feet, forming a short tree or dense shrub shape with multiple stems. The leaves are smaller than most other deciduous trees, but broad, and are rounded in shape with serrated edges.
Small male catkins and clusters of female flowers form in the spring. The fruits or nuts – the hazelnuts – grow inside short green, fuzzy husks that don't completely cover the nuts and are found underneath the leaves of the plant.

The nuts will be ripening in September leading up to October harvest. They are ready to eat when the leaves of the tree are turning yellow and the fuzzy outer husks splits and exposes its hard brown shell, which must be cracked open to obtain the edible kernel, aka the hazelnut. Around this time you also begin to find hazelnuts on the floor.
If you have squirrels in your neighbourhood, beware! The squirrels begin feasting as soon as the nuts are ripe enough to eat, but still in the tree, and they will clear a shrub of nuts within a short amount of time, eating some and burying the most. So don't waste your time if you also want a part of the bounty! (Lucky for us, the squirrels usually don't find all of the nuts they have buried in autumn, so when spring rolls around you will probably find a few baby hazelnut trees nearby.)

Speaking of squirrels, hazelnuts are full of healthy fats, protein and vitamins, which makes them an important source of food for wildlife, who depend on hazelnuts to give them energy for the winter, so make sure you do not gather all of the nuts you find!

The best time to pick hazelnuts is when the outer husks turn a yellow colour in late September or early October, prior to the autumn rains. A good shake of the tree should loosen more for you to gather from the ground.

Some of the fallen nuts may be wormy or even empty. It is easy to distinguish between those nuts that are bad from good. Place the nuts in water. Floating nuts are the duds. Discard any floaters. Also, insect infested nuts will have holes in the shell and should be tossed out.

Hazelnuts can be eaten fresh from the tree or stored for later use.
When fresh, they have s sweet, pea-like flavour. To store fresh nuts, pack in a box or bowl with damp sand, and check regularly for mould. They should last 3 to 4 months before they begin to sprout.

To extend their storage life and getting that familiar nutty flavour, I suggest drying the hazelnuts (either in their shells or shells removed) by storing in a single layer on a screen in a dry, warm, airy place for 2 to 4 weeks. Stir them around every day. To be extra sure all the moisture is gone, place them in the oven on low heat (170 F / 75 C) for about 1 hour before storing in an airtight container.

Whether scattered over salads, as part of a homemade granola, or blended with water and strained through a nut milk bag to make a delicious nut milk – hazelnuts are delicious, both roasted and raw! (When making that hazelnut milk, save the pulp to make cookies or porridge!) You can also grind them in dried form to make flour for cakes, breads or biscuits. Another great way to use hazelnuts is to through them into a food processor and blend them until they turn into a delicious nut butter. Homemade healthy nutella anyone?

Not only the nuts of the hazel are considered edible. In spring (April to June) you can harvest the young and tender leaves that are light green in colour and still very soft. Those can be used to make tea, or to make stuffed hazelnut leaves. Perhaps I can get my hands on some tender hazelnut leaves next spring ... Leaves picked later than that are leathery and not suitable for consumption.

General Foraging Guidelines:

  • You should be 100 % certain you are identifying the correct plant. If you do not know what it is, DO NOT eat it! Do not pick if you're in doubt!

  • Don't harvest from contaminated areas such as busy roadsides, near industrial facilities, where dogs pee, along the edges of agricultural fields, old landfill sites etc.

  • Be mindful & harvest sustainably. Only pick from areas that have a plentiful supply, and never more than 1/4 of a plant, ideally only about 5 %.

  • Leave the harvesting area litter-free.


Preparation time: 1 h 15 min
Main ingredients: blueberries, hazelnuts, oats
difficulty level: easy
makes: 8-12 bars
suitable for: vegan, lactose-free, wheat-free, soy-free


Crust & Crumble Topping:
1 1/2 cups (150 g) + an extra 1/2 cup (50 g) old-fashioned rolled oats
1 cup (130 g) whole-grain spelt flour (or sub gluten-free flour)
2/3 cups (85 g) hazelnuts
3/4 cup (75 g) raw cane sugar or brown sugar
1/2 tsp cinnamon
1/4 tsp nutmeg
1/2 tsp of salt
4 tbsp + an extra 1 tbsp coconut oil, melted then cooled to soft (or sub vegan butter)
3 tbsp hazelnut butter (or sub more coconut oil or vegan butter)
3 tbsp non-dairy milk (e. g. soy, oat, almond or hazelnut)

3 cups (430 g) blueberries, fresh or frozen (or sub other berries or fruit, see notes below)
pinch of salt
zest and juice of 1 organic lemon
2 tbsp cornstarch
1 tsp vanilla extract
1 tbsp maple syrup


Line a 9x9 brownie pan with parchment paper. Preheat oven to 350 °F / 180 °C.

For the crust:

Blitz rolled oats (reserve 1/2 cup / 50 g for later), flour, and hazelnuts to a food processor until you have a coarse, chunky flour *. Add to a medium mixing bowl, along with sugar, cinnamon, nutmeg and salt. Mix well. Add in coconut oil (reserve 1 tbsp for later), hazelnut butter and non-dairy milk, and incorporate with a fork or pastry cutter until the dough looks crumbly. The mixture should hold together when pressed down with a spoon.

Spread a little more than half of the crumble mixture into the prepared baking dish. Use your hands or the bottom of a measuring cup to firmly press down. Try to make sure it's all an even thickness.

Set the rest of the crumble dough aside for later.
For the filling:
In the mixing bowl, toss together the berries, salt, cornstarch, vanilla extract, maple syrup, lemon zest and juice of that lemon.
Spread the blueberry mixture evenly on top of the prepared crust. They should just cover the crust in one layer.

For the crumble topping:

To the remaining crumble dough, add 1/2 cup (50 g) rolled oats and 1 tbsp coconut oil. Use your hands to press the dough together into small to medium clumps.
Sprinkle the crumble topping over the blueberry layer. Place in the oven and bake for 40–45 minutes, or until the crumble starts to turn golden brown and the filling is bubbling along the edges.

Remove and let cool completely (while you clean up the mess you've made in the kitchen and put away clean dishes).

Or – if you are too impatient, like yours truly – you can let the crumble rest for just 5 to 10 minutes before cutting into it and eating it like a classic fruit crumble. When serving these warm, you've got to put on a scoop of (vegan) ice cream!

Once cooled, use the parchment paper to lift the crumble bars from the pan and place on top of a cutting board.

You can enjoy the vegan blueberry hazelnut crumble bars immediately, store in the fridge in an airtight container for up to 4 days, or freeze to enjoy for weeks to come.


- You can easily substitute the blueberries in this recipes with blackberries, raspberries, strawberries, gooseberries, redcurrants or cherries. Even plums, pears or apples would be lovely and matching the warming, autumnal flavour of the hazelnuts, cinnamon and nutmeg.
- Instead of hazelnuts, you could also use walnuts or almonds (and almond butter). You probably could also use sunflower seeds (and sunflower seed butter) to make these nut-free, but I have not tried that yet.
- * If you don't have a food processor, simply chop the nuts as finely as you like, and stir together with rolled oats and flour. Instead of your hands you could use an electric mixer with a dough hook to help incorporate everything.
- These bars actually get better as they sit. I like them best on day 2 and 3.
- To freeze, place cut bars in freezer-safe zip-top bag, and freeze up to 3 months. When ready to eat, take individual bars out and let thaw to room temperature. I recommend warming them up in the microwave or the oven, and serving them with a dollop of vanilla sauce or ice cream. Yum!