Preheat the oven to 350 degrees F (175 degrees C).
Beat butter and sugars with an electric mixer until light and fluffy. Beat in eggs and vanilla extract. Blend in flour, baking powder, cinnamon, and salt. Mix in oats and 1 cup chocolate chips.
Spread batter evenly in an ungreased 9x13-inch baking pan. Sprinkle remaining 1 cup chocolate chips evenly on top.
Bake in the preheated oven until edges are browned and center is light brown, 20 to 22 minutes. Do not overbake. Cool completely before cutting into 24 bars.