TBT Recipe: Christmas Breakfast Chocolate Sour cream Crumb Cakes - Cooking by the Book

Ingredients

• ½ cup all-purpose flour
• ½ cup walnut halves, toasted and coarsely chopped
• ¼ cup tightly packed light brown sugar
• 4 tablespoons (½ stick) unsalted butter, cut into small pieces
• ⅛ teaspoon ground cinnamon
• ¼ teaspoon salt
• 1 ½ cups all-purpose flour
• ¼ cup unsweetened cocoa powder
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• ½ teaspoon salt
• 1 cup granulated sugar
• 8 tablespoons (1 stick) unsalted butter, cut into 1-tablespoon pieces
• 2 large eggs
• 2 ounces semisweet baking chocolate, coarsely chopped and melted
• ½ cup buttermilk
• ½ cup sour cream
• 1 teaspoon pure vanilla extract