Preheat oven to 350°F (175°C) and grease a 9-inch cake pan.
In a bowl, mix flour, baking powder, baking soda, and salt.
Cream butter and sugar until fluffy.
Add eggs one at a time, mixing well after each.
Stir in sour cream and vanilla.
Gradually fold in dry ingredients until just combined.
Gently mix in chocolate chips.
Pour batter into the pan and spread evenly.
For topping, combine flour, brown sugar, melted butter, and cinnamon. Sprinkle over the batter.
Bake for 40 minutes or until a toothpick inserted comes out clean. Cool before slicing.