My husband's favorite fruit is blueberry, so every summer we make something blueberry-filled to celebrate.  One of the favorites has been the little blueberry-banana cakes - or sometimes we go for lemon-blueberry or just straight blueberry flavors, but this summer I got to thinking that chocolate covered blueberries are tasty - so why not make a chocolate blueberry birthday cake!  This uses the blueberry filling from our favorite blueberry cream cheese pie, then has layers of a light spongy chocolate cake and chocolate ganache.  Yum!  It was absolutely delicious! And it slices up beautifully, too! Enjoy!

Blueberry & Chocolate Birthday Cake, ready for the ganache writing on the top!

Fancy ganache writing on top - if you time it right, the ganache just barely melts into the top layer, creating a beautiful look.

A slice of blueberry chocolate cake! 

Blueberry & Chocolate Birthday Cake!

Blueberry Filling:

In a medium saucepan, combine and heat over medium heat: 
300 g (11 oz) frozen wild blueberries
1/3 cup sugar
2 Tbsp water
pinch of salt
Let cook, stirring occasionally, until boiling.

Whisk together in a small bowl:

2 1/2 Tbsp water

2 1/2 Tbsp cornstarch

Add cornstarch mixture to boiling blueberries, stirring constantly.  Bring mixture back to a boil and let boil a few minutes until mixture has thickened (keep stirring).  Remove from heat and add: 
1 1/2 - 2 tsp butter

Scoop into a wide, low bowl and cover with plastic wrap on surface.  Set aside to cool.  

Chocolate Sponge Cakes:

Preheat the oven to 350 F.  Butter the edges and line 2 quarter sheet baking pans with parchment paper (quarter sheet baking pans are approx 8x12 inner dimension or 9x13outer dimension metal cookie sheets - I LOVE this size.  Perfect for the toaster oven, and perfect when you have multiple things you want to roast separately in the regular oven, and of course, opera-style cakes!)

Melt together, then set aside:

1/4 cup butter

1/4 cup dark chocolate chips

In a small measuring cup, combine to make a "buttermilk": 

2 Tbsp white vinegar

milk to equal 1 cup (lactose-free or milk substitutes work)

In a large bowl, whisk together: 

1/2 cup coconut flour

1/4 cup cocoa powder (extra dark works nicely in this recipe)

1/4 cup white rice flour

1 cup sugar

1/2 tsp baking soda

1/2 tsp salt

Add and whisk in until smooth: 

1 cup buttermilk, from above

melted butter & dark chocolate, from above

1/4 cup oil

6 large eggs

2 tsp vanilla bean paste or vanilla extract

Batter whisked and ready to put into the prepared pans.

Divide between the two parchment-lined pans.  Bake at 350 F for approximately 15-18 minutes.  These are nice and thin, so they cook quickly.  They should look nicely dried, but not burned or too dark on the edges. They should look no longer wet in the center.  Depending on your oven, they may need an extra minute or two.

Batter divided and ready for baking.

Out of the oven.  You can see how it's nicely dried out. Chocolate cake always smells so good. 

Remove from oven.  Let rest 5 minutes before flipping onto cooling racks to cool.  Once cool, carefully slice each cake in half so you'll have four even layers for your cake. 

When the cakes and blueberry filling are just about cooled, prepare the ganache. 

Chocolate Ganache

In a small frying pan, heat over medium heat until just starting to bubble nicely: 

1/4 cup heavy whipping cream

1/4 cup butter

1 tsp vanilla bean paste (or extract)

Remove from heat and pour over (in a bowl): 

5 oz high quality semi-sweet chocolate chips

Stir until ganache is smooth.  Let cool ~5 minutes before assembling cake.  

Assembling Cake

Layer cake in the following order:

1. Cake

2. 1/3 blueberry filling, gently spread over cake layer

3. Drizzle of chocolate ganache

4. Repeat 2 times (cake, blueberry, ganache drizzle)

5. Top with 4th layer of cake

6. Spread most of the remaining ganache gently over the top, reserving some for decoration

Chocolate cake, a layer of blueberry filling, and a drizzle of chocolate ganache. 

Repeated for each layer.

Finally, topped with the final layer of cake and drizzled with "most" of the remaining ganache - saving a bit for the final writing on top!

Let remaining ganache cool an additional few minutes, then put it in a ziploc bag.  Snip the corner and pipe desired decoration on top of your cake.  Serve immediately, or refrigerate until ready to serve.  Let rest at room temperature 20-30 minutes before slicing to let the ganache warm a bit before slicing.

Ganache decoration on top!

Once it's chilled, it looks like this. 

Yum yum yum!

Blueberry & Chocolate Birthday Cake Recipe by Successfully Gluten Free!