Nothing says Happy 89th Birthday like a hamburger cake. But when my six year old read about it in a Food Network Kids Cookbook, she was convinced it would be the perfect cake for her great-nana. So, we turned it into a gluten-free, chocolate party cake. And it really was - lots of laughs, and packed with delicious chocolate in both batter and frosting, it was a hit!
Happy 89th Birthday to this festive nana! We'll have to see if we can top it for your 90th. Maybe a hot dog cake? By the time we served the cake, the hot kitchen had made the marshmallow fondant stretch and "melt" just like real cheese. Ha!
My sister-in-law snapped this photo of the cake.
Just after finishing our "burger" cake.
Hamburger Cake
You can make the cake batter below, which is based off my chocolate chocolate chip muffin recipe. It is rich and tasty - although I prefer it made fresh. Other GF cake options that would work well in this recipe are my delicious chocolate cake recipe, my chocolate & toasted marshmallow chocolate cake, or a GF cake of your choice. You could even use a vanilla cake, like the one in my blackberry vanilla cake recipe (double the recipe if you make it for a hamburger cake), if you prefer.
Preheat oven to 350 F. Butter three 6" cake pans and line the bottoms with a piece of parchment paper. Have an extra muffin tray available to make chocolate chip muffins with any of the batter you don't use. I made 6 muffins.
In a small measuring cup, stir together and set aside:
1/2 cup boiling water
1/2 cup boiling water
1/2 cup cocoa powder
In a mixing bowl, mix together: (it's important to mix dry ingredients first in gluten-free baking to avoid clumps)
1 cup brown rice flour
3/4 cup white rice flour
1/3 cup arrowroot starch OR cornstarch
1/4 cup potato starch
1/4 cup tapioca starch
1 1/2 tsp xanthan gum
1 tsp salt
1 Tbsp baking powder
2 tsp baking soda
Add and mix in, letting it beat until it's nice and smooth:
cocoa mixture, from above
1 cup butter, softened
2/3 cup milk
2/3 cup sour cream OR plain or vanilla greek yogurt
4 eggs
1 cup white sugar
1/2 cup brown sugar
Add and mix in:
3 cups chocolate chips (variety - dark, semi, milk, white)
Divide the batter into the three prepared 6" cake pans. I had just enough batter leftover for 6 chocolate chip muffins. So, most of the batter will go into the cakes. They will double in size while baking, so make sure your tins are nice and tall.
Ready to bake!
Bake cakes at 350 F for 35 - 40 minutes. Remove from oven and let rest 10 minutes before removing from pan (and removing parchment paper from the bottom) and placing them to cool on wire racks. I highly recommend using a gentle fan to help these cool faster. Anything with chocolate in it will take longer to cool.
Fresh from the oven.
Cooling with the help of a small fan. It made it cool MUCH faster.
Prepare the following about 30 minutes before you plan to assemble your cake:
1. Homemade marshmallow fondant (for the cheese)
2. Chocolate Frosting + Vanilla Frosting (which gets some of the chocolate added into make the color perfect for the bun)
3. Flattened watermelon gummies (for the lettuce/tomatoes)
Marshmallow Fondant
In a large glass bowl, heat in a microwave at 20 - 30 second increments until nice and puffy and melted, stirring occasionally:
5 oz large marshmallows
Stir in with hands, kneading well:
3/4 cup sifted powdered sugar, keeping an extra 1/2 cup available in case extra is needed
1 - 2 tsp water
Knead and stretch the marshmallow fondant in the bowl to help avoid as much of a mess with the powdered sugar. If you want to tint it with a bit of yellow/orange/red food coloring, you can do so, and knead and stretch it in.
Keep the marshmallow fondant wrapped tight in plastic wrap until you're ready to roll out and assemble on your cake. You will roll it out on a cutting board (or countertop) sprinkled well with powdered sugar. Keeping the rolling pin, fondant, and board well sprinkled with powdered sugar will help avoid any stickiness. You can slice it carefully with a sharp knife into a square shape to be placed on the cake "hamburger" once rolled out.
Make sure to cut your square so it's width matches the diameter of your cake or you'll end up with it a little large, like we ended up doing. Still fun - and looks like melted cheese.
You can also see the darker chocolate frosting on the middle (hamburger) section and the lighter chocolate/vanilla mixed frosting making up the top and bottom sections.
Chocolate and Vanilla Frosting
In a mixer, beat until light and fluffy:
1/2 cup butter, softened
3/4 cup powdered sugar
1/4 cup cocoa powder
1 tsp vanilla
1 cup marshmallow fluff
Remove from mixer into another bowl. Add and beat in the same mixer until light and fluffy (it's OK to have any leftover chocolate frosting in there, since you'll be adding some of the chocolate frosting in later to make a light brown "bun" color):
1/2 cup butter, softened
1 cup powdered sugar
1 tsp vanilla
1 cup marshmallow fluff
Add some of the chocolate frosting to the vanilla frosting until you have the desired "bun" color lighter frosting.
Lettuce Leaves
On a cutting board or counter sprinkled with regular sugar, roll gummy watermelons as flat and wide as you can. Flipping over regularly to add extra sugar to it as it flattens so they don't end up sticky. You will pinch together the red ends, and place them in a circle around the cake after you've frosted the bottom layer, so the "lettuce" part is sticking out the edges.
All prepped and ready for the "burger" - my 6 year old loved this part.
To Assemble the Hamburger Cake:
Trim the cakes:
1. Bottom layer - slice a cake in half until you have a 1 - 1 1/2 " flat slice of cake
2. Middle layer - slice off the top of the cake until you have an ~2 - 2 1/2" piece of cake
3. Top layer - with a sharp knife, carefully trim the top layer until you have a nice, domed piece of cake
Take some of the trimmed cake and crumble it up to decorate the sides of the middle layer.
On the bottom layer spread the top and sides with the light chocolate frosting. Decorate the edges with the flattened watermelon gummies.
On a separate plate or holding in the air, spread the top and sides of the middle layer with the dark chocolate frosting. Press the cake crumbs onto the sides of the layer. Gently place it on top of your bottom layer/lettuce leaves.
Roll out and trim your rolled out marshmallow fondant into a square that has a length the same diameter as your cake. Place it on top of your hamburger layer.
Gently place your top domed layer of cake on top of the fondant square. Spread the top layer with the remaining light chocolate frosting.
If desired, press puffed rice cereal into the top to look like sesame seeds.
To serve, I highly recommend slicing the cake in half, laying it flat and cutting wedges of "burger" out that way. It makes it easier to work with/cut into the marshmallow layer. Enjoy!
A seriously happy baker putting puffed rice "sesame seeds" on top of the burger cake.
