This is a simple and super easy chocolate cake recipe that is made in one bowl, in a single layer and with a simple rich chocolate buttercream frosting. It's no-fuss and incredibly satisfying!
Preheat oven to 350°F. Line an 8-inch round cake pan with parchment paper.
Sift flour, cocoa, baking powder and baking soda into a large bowl. Add sugar and salt and whisk to blend well.
Combine egg, melted butter, sour cream and vanilla in a medium bowl and whisk to blend well. Pour it into the bowl with the dry ingredients and mix with an electric hand mixer on medium-low until blended. It will be thick and somewhat dry. Add the hot coffee gradually in two stages to minimize clumps forming and beat until evenly combined and the batter smooth.
Pour batter into prepared pan and bake for 25-30 minutes until cakes spring back when pressed gently and a skewer inserted into the center comes out clean. Transfer pan to a wire rack and let cool for 15 minutes before inverting onto the rack to cool completely.
For the frosting, beat butter with sifted icing sugar, vanilla and salt in a medium bowl until very pale and creamy. Add cooled melted chocolate and mix on low speed just gently until combined. Add milk and sour cream one tablespoon at a time and mix gently until it reaches a smooth spreading consistency. Use it immediately to frost the cake and enjoy!