Preheat the oven to 350 degrees . Grease an 8-inch square baking pan. In a medium bowl, mix together the flour, baking powder, baking soda and salt. In a small bowl, combine 1/4 cup sugar and the cinnamon.
Using an electric mixer, beat together the butter and remaining 1 cup sugar until fluffy, about 5 minutes. Beat in the eggs, 1 at a time, then beat in the sour cream and vanilla. Fold in the flour mixture, in 2 parts, until just combined. Pour half the batter into the cake pan and sprinkle with half the cinnamon-sugar and half the chocolate chips. Spoon the remaining batter as evenly as possible over the filling, spreading gently. Sprinkle with the remaining cinnamon-sugar and chocolate chips.
Bake until golden and a toothpick inserted in the center comes out clean, 30 to 35 minutes.