For the cake
1 1/2 cups (210 g) all-purpose gluten free flour (I used my Better Than Cup4Cup blend, but any of the others should work fine)
3/4 teaspoon xanthan gum (omit if your blend already contains it)
14 tablespoons (70 g) unsweetened cocoa powder (I prefer Dutch-processed in this recipe, but made it with natural cocoa powder and it worked fine)
1/2 teaspoon kosher salt
1/2 teaspoon baking soda
1 cup (200 g) sugar
3/4 cup (168 g) sour cream, at room temperature
1/2 cup (112 g) vegetable oil
2 eggs (120 g, out of shell) at room temperature, beaten
3/4 cup (6 ounces) warm water (about 95°F)
For the ganache topping
3/4 cup (6 fluid ounces) heavy whipping cream
8 ounces (or 10 ounces, for whipped ganache) dark chocolate, chopped
1 cup (115 g) confectioners’ sugar (for whipped ganache)
Preheat your oven to 350°F. Grease a 9-inch round or square baking pan and set it aside.
In a large bowl, place the flour, xanthan gum, cocoa powder, salt, baking soda and sugar, and whisk to combine well. Create a well in the center of the dry ingredients and add the sour cream, oil, eggs and water, mixing to combine after each addition. The batter should be very thickly pourable. Scrape the batter into the prepared pan, smooth into an even layer and place in the center of the preheated oven. Bake until a toothpick inserted in the center of the cake comes out mostly clean or with a few moist crumbs attached (about 30 minutes). Do not overbake. Remove from the oven and allow to cool for 10 minutes in the pan before inverting onto a wire rack to cool completely.
While the cake is cooling, make the ganache topping. In a small, heavy-bottom saucepan, heat the heavy whipping cream until it just begins to simmer. Place the chopped chocolate in a medium-size bowl, and pour the hot cream over the chocolate. Allow the cream to sit on the chocolate for about a minute, until the chocolate begins to melt, and mix until the chocolate is melted and the mixture is smooth and glossy.* Pour the warm ganache over the top of the cooled cake, and gently spread toward the edges so the ganache begins to drip down the sides of the cake. Allow to set at room temperature before serving.
*To make whipped ganache frosting, use 10 ounces of chopped chocolate with the 6 fluid ounces cream and follow the same instructions. Allow the ganache to cool at room temperature until no longer hot to the touch. Cover and place in the refrigerator until firm enough to scoop with a spoon. Transfer the cooled ganache to a large bowl and beat with a handheld mixer or stand mixer fitted with the whisk attachment until thickened and fluffy. The ganache will also lighten in color. Add the optional confectioners’ sugar and beat until well-combined. Frost as desired.
This recipe was first published on the blog in 2014. The photos are updated but the recipe remains the same.