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)

GANACHE TOPPING (optional)
3/4 cup (6 fluid ounces) heavy whipping cream

8 ounces dark chocolate, chopped