Gluten Free Blueberry Streusel Cake (Heidelbeerkuchen)

Let's talk about this Gluten Free Blueberry Streusel Cake—a delicious twist on my Gluten Free Rhubarb Streuselkuchen. A moist and tender cake packed with juicy blueberries that burst with every bite. Topped off with a generous layer of brown sugar streusel, this cake pairs perfectly with your morning coffee or makes for a sweet treat during an afternoon break.

Recipe Ingredient Notes

Gluten Free Flour: To test this Gluten Free Blueberry Streusel Cake Recipe, I have used my own gluten-free flour blend and King Arthur Measure for Measure. Both of these blends yielded a tender, moist crumb and provided an outstanding flavor. It's worth noting that while I haven't tried other brands of flour in this recipe, it doesn't necessarily mean that they won't work.

Almond Flour: The almond flour gives the Heidelbeerkuchen its beautiful structure and moist crumb. If you prefer to keep this recipe nut-free, please substitute the almond flour with the same amount of gluten-free flour. You can also substitute the almond flour with hazelnut flour or walnut flour.

Milk: This recipe works great with milk (any percentage), non dairy milk or even water. I like to use milk since the lactose found in milk helps the cake with browning.

Oil:  The tenderness of this quick and easy cake comes from vegetable oil since it stays liquid even after cooling. Cakes made with butter normally should be brought to room temperature before serving. I use grapeseed oil in my baking but a neutral oil such as vegetable oil will work just fine.

Blueberries: Fresh or frozen blueberries work here. If you use frozen berries, there is no need to thaw them ahead of time. I do recommend tossing them in some flour though since frozen blueberries tend to contain more moisture.

Brown Sugar Streusel

It's no secret that I love a good streusel topping for my coffee cakes. This recipe makes enough for one 8"x8" baking pan. You can replace some of the gluten-free flour with gluten-free oats or nuts such as walnuts, pecans, or almonds.

1. Melt the unsalted butter in a small pot on the stove or in a microwave-safe bowl. Let it cool for a few minutes. This won't take long since it's such a small amount of butter.
2. Meanwhile, combine the gluten-free flour, light brown sugar, ground ginger (or ground cinnamon), and kosher salt in a mixing bowl and whisk together.
3. Using a fork or a small spatula, lightly mix the dry ingredients and melted butter together until crumbles form. Don’t overmix.
4. Place the brown sugar streusel in the fridge while you prepare the gluten free cake batter for the Heidelbeerkuchen. You can freeze the crumb topping for up to 3 months.

Blueberry Streusel Cake Batter

This blueberry streusel cake comes together in no time. You will need two mixing bowls: one for whisking the egg whites and another for the wet ingredients. I use a hand mixer for the egg whites and a bowl and whisk for everything else.

1. Start by preheating your oven to 350°F. Spray an 8x8 baking pan with cooking spray, line it with parchment paper, and set it aside.
2. In a small bowl, combine the gluten-free flour, almond flour, kosher salt, and baking powder. You can either whisk or sift the dry ingredients together. Just make sure they are fully combined and there are no clumps.
3. In another mixing bowl, combine the granulated sugar and lemon zest. Be sure to set aside 20 grams of sugar for the egg whites. Use the back of a spoon or your clean hands to rub the zest into the sugar. This will intensify the lemon flavor, giving the coffee cake a subtle lemony hint.
4. Carefully separate the eggs, placing the egg yolks into the bowl with the lemon sugar and the egg whites into a clean mixing bowl. Set the egg whites aside for now.

5. Whisk the lemon sugar and egg yolks together until the mixture becomes lighter in color and doubles in volume.
6. Add the oil and milk (or water) and vanilla extract to the egg yolk mixture and whisk until smooth. Set it aside while you prepare the egg whites. During my recipe testing, I found that adding the dry ingredients to the wet mixture at this point makes the batter too stiff, making it difficult to fold in the egg whites. Therefore, I suggest waiting to add the dry ingredients until after you have whisked the egg whites.

7. Using an electric hand mixer (or a stand mixer), beat the egg whites with a pinch of salt until frothy. Gradually add the reserved granulated sugar, mixing until the egg whites become glossy. Aim for soft to medium peaks; overmixed egg whites will look dull and dry.
8. Incorporate the dry ingredients into the wet mixture in two parts, whisking until the batter is smooth.
9. Gently fold about a third of the beaten egg whites into the batter to lighten it. Then, carefully fold in the remaining egg whites until the batter is light and airy. Be sure to fold gently and avoid overmixing.

Baking Instructions

Make sure your oven is preheated to 350°F, and have your blueberries and streusel topping ready.

1. Pour the gluten free cake batter into the prepared baking dish. Use a small offset knife or the back of a spoon to spread it evenly.
2. Evenly sprinkle the fresh blueberries over the cake batter; there's no need to press them in. If you use frozen blueberries make sure to toss them in some gluten free flour (around 1 tablespoon) before using them to top the cake.
3. Generously top the cake with the brown sugar streusel, allowing some of the fruit to peek through.
4. Bake the Gluten Free Blueberry Streuesel Cake at 350°F for 34-38 minutes. It should be golden brown, and a cake tester or toothpick inserted into the center should come out clean. If using a digital thermometer, ensure the internal temperature at the center of the cake reaches above 200°F.
5. Once baked, remove the coffee cake from the oven and place it on a cooling rack. Let it cool in the pan for at least 15-20 minutes before serving.

Serving Idea

I love serving this Gluten Free Blueberry Streusel Cake still slightly warm from the oven. Dust the cake with some powdered sugar and if you like, top each slice with a generous dollop of freshly whipped cream or a scoop of vanilla ice cream.

Storage & Freezing

Although this quick and easy heiselbeerkuchen is delicious the day it was baked, it is delightful the next day. To store any leftovers, keep them in an airtight container at room temperature for 3-4 days. If it’s hot and humid in your kitchen I recommend storing it in an airtight container in the fridge. Cakes containing fresh fruit tend to spoil quickly. Allow for it to come to room temperature before serving

To freeze pieces of the cake, make sure it is completely cool. Freeze individual pieces in an airtight container for up to 2 months. Thaw at room temperature.

Tips for whipping egg whites

Here are some tips to help you whip egg whites to make a light and tender Gluten Free Blueberry Streusel Cake.

• Use a Clean Bowl: Ensure your mixing bowl and beaters are completely clean and free from any grease or residue, as this can prevent the whites from whipping properly.
• Separate Eggs Carefully: When separating eggs, be careful not to get any egg yolk into the whites. Even a small amount of yolk can inhibit proper whipping.
• Start Slow, Increase Speed: Begin whipping the egg whites at a low speed to break them up, then gradually increase to medium-high speed as they start to foam.
• Watch for Stiff Peaks: Whip the egg whites until they form stiff peaks that hold their shape when the beaters are lifted. Be careful not to overbeat, as this can cause the whites to become dry and lose their volume.

Note about Salt in my Recipes

I use Diamond Kosher Crystal Salt in all of my recipes unless otherwise stated. If use use a different brand or kind of salt in your kitchen please adjust accordingly since some salts can be saltier. If you use Morton’s Kosher Salt please be aware that their salt granules are smaller in size, denser, and crunchier and twice as salty.

Baking in grams

I share my recipes in grams and by weight since baking by weight is the most accurate way to bake. Digital Scales are very affordable and easy to use. You can purchase them on Amazon for less than a set of measuring cups. For small amounts under 10 grams, I like to use this Precision Pocket Scale. Measuring cups are very inaccurate which can cause significant errors when it comes to gluten-free baking or baking in general. Especially since I bake with gluten-free flours which weigh differently than “regular” flours. I do provide some ingredients like spices and leavening agents in measuring spoons. To learn more about Baking with a digital scale, make sure to check out my post about Baking by weight.

Note about Ovens and Oven Temperatures

All my recipes are tested and developed with a conventional oven. I always bake my baked goods on the rack placed in the MIDDLE of my oven. This way the heat coming from the bottom will not burn my baked goods.

If you are baking with convection (fan-forced), please adjust the recipes accordingly. Convection oven can cause baked goods to dry out quickly and still be raw inside. Since takes at least 15-20 minutes for a standard American Oven to be fully preheated. I highly recommend investing in an Oven Thermometer.

Substitutions and Modifications

Any dietary or ingredient modifications/substitutions to this recipe may alter the end result in appearance and taste. I test my recipes several times as published in this post and The Gluten Free Austrian Blog is not responsible for the outcome of any recipe you find on our website.