Chocolate Potato Cake

Preheat the oven to 350°F and grease two 8-inch round cake pans, then line the bottoms with parchment paper.

Cream together the softened butter and granulated sugar in a large mixing bowl until light and fluffy, about 2-3 minutes.

Add the eggs one at a time to the butter mixture, beating well after each addition to incorporate air into the batter.

Stir in the melted unsweetened chocolate and vanilla extract until the batter is evenly colored and well combined.

Fold in the cold mashed potatoes gently using a spatula until no lumps remain and the mixture is uniform.

Whisk together the sifted all-purpose flour, baking soda, and salt in a separate bowl.

Alternate adding the flour mixture and sour milk to the chocolate-potato batter, beginning and ending with the flour mixture, stirring gently until just combined.

Divide the batter evenly between the prepared pans and smooth the tops with a spatula.

Bake in the preheated 350°F oven for 35 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cakes from the oven and let them cool in the pans for 10 minutes before turning them out onto a wire rack to cool completely.