From: Art of Gluten-Free Baking (http://artofglutenfreebaking.com)
Yield: 1 two layer (8 or 9 inch) layer cake
Note: This recipe uses my flour mix, Jeanne’s Gluten-Free All-Purpose Flour Mix (mix together and store in a cool, dark place, or in fridge for long-term storage). 1 cup of this mix equals 140g. Use this mix cup-for-cup or gram-for-gram in all of your recipes:
1 1/4 cups (170 g) brown rice flour
1 1/4 cups (205 g) white rice flour
1 cup (120 g) tapioca flour
1 cup (165 g) sweet rice flour (also known as glutinous rice flour, or under the brand name, Mochiko)
2 scant tsp. xanthan gum
For the cake
2 1/4 cups (315 g) Jeanne’s Gluten-Free All-Purpose flour mix
2 teaspoons baking powder
1/4 teaspoon salt
1 cup (2 sticks; 230 g) unsalted butter at room temperature
1 package (8 oz; 230 g) cream cheese, room temperature
1 1/2 cups (300 g) granulated sugar
2 tablespoons gluten-free sour cream
1 teaspoon vanilla extract
4 extra large eggs, room temperature
1 cup (6 oz; 170 g) semi-sweet chocolate chips
For the frosting
2 1/2 cups (15 oz; 425 g) semi-sweet or bittersweet chocolate, chopped or in chips
1 teaspoon instant coffee (I use decaf Starbuck’s Via) (optional)
2 1/4 cups (16 oz; 455 g) gluten-free sour cream, room temperature
1 tablespoon honey
3/4 teaspoon vanilla extract
Preheat oven to 350 degrees F/180 degrees C/Gas Mark 4. Line the bottom of two 8 in or 9 in round cake pans with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter on medium high for 2 minutes, until light and fluffy. Add the cream cheese and beat on medium high for 2 more minutes. Scrape down sides. Add the sugar, and beat on medium high for 1 minute. Add the sour cream and vanilla extract and beat until combined. Scrape down sides. Add eggs, one at a time, beating after each addition. Scrape down sides. Add the flour mixture and beat until combined. Remove bowl from mixer and mix in chocolate chips by hand.
Scrape batter into prepared cake pans. The batter is quite stiff–so you will need to push it around it to fill out the edges and to smooth the top.
Bake at 350 degrees until a cake tester comes out clean–about 30 minutes for 9 inch pans and 40 minutes for 8 inch pans. Let cake cool in pans for 5 minutes. Release onto wire racks, remove parchment paper, and let cool completely before frosting.
To make the frosting
While the cake is cooling, make your frosting. In a heavy-bottomed sauce pan set over low heat, heat chocolate until just barely melted. Watch carefully so it doesn’t burn. Once melted, remove from heat and whisk to smooth. Add instant coffee powder, if using, a whisk to combine. Let sit for a few minutes until the chocolate has cooled to room temperature. Add sour cream and whisk until well-combined. This will take a bit of whisking. Add honey and vanilla extract and whisk until combined and frosting is smooth.
Set aside frosting at room temperature until cake is completely cool. The frosting should firm up a bit and become a thick, spreadable consistency. If you want to speed up this process, stick it in the fridge for awhile, about 30 minutes. My kitchen tends to be on the cool side, so I just let it firm up on the counter. This makes more than enough frosting for a typical 2 layer cake.
To frost the cake
Place the bottom layer on a serving plate, top side down (so the side that the parchment paper was on is up). I like to add a dab of frosting on the middle of the plate and place the cake layer down on top of it–this will help the cake stay in place. Frost the top of this layer. Place the top layer on top of the frosting, top side down. Frost the top layer and then frost the sides. Smooth all. You will find that you have more than enough frosting. Store the leftover frosting in a jar in the fridge and use as a midnight treat .