Preheat the oven to 350°F 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. Spread half the batter into the cake pan and sprinkle with half the cinnamon-sugar and half the chocolate chips. It's ok to just put it in the middle and gently even out. It may not touch the edges of the pan but will spread out when cooking. 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.