Peanut oil, for frying
4 cups all-purpose flour, plus more for dusting
1 cup sugar
1/2 cup unsweetened cocoa powder
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup sour cream
1/2 cup milk
2 large eggs
2 (1-ounce) squares white chocolate
4 tablespoons heavy whipping cream, divided
2 (1-ounce) squares bittersweet chocolate
2 tablespoons heavy whipping cream
In a large Dutch oven, pour the oil to a depth of 2 inches; heat to 360 degrees F.
In a large bowl, combine the flour, sugar, cocoa, baking powder, baking soda, and salt.
In a small bowl, whisk together the sour cream, milk, and eggs. Add to the flour mixture, stirring to combine.
Turn the dough out onto a lightly floured surface. Roll to 3/4-inch thickness. Using a 3-inch round cutter, cut out the doughnuts. Using a 1-inch round cutter, cut out the center of each doughnut.
Fry the doughnuts, in batches, for 1 minute per side. Drain on paper towels.
In a small bowl, combine the white chocolate and 2 tablespoons heavy cream. Microwave on High in 30-second intervals, stirring between each, until the chocolate is melted and smooth (about 1 minute total). Drizzle over the doughnuts.
In a small bowl, combine the bittersweet chocolate and remaining 2 tablespoons heavy cream. Microwave on High in 30-second intervals, stirring between each, until the chocolate is melted and smooth (about 1 minute total). Drizzle over the doughnuts.