Combine the brown sugar, flour, oats, and baking powder in a bowl. Cut in the butter to make the crust and crumble topping.
Add half of the crust to a 8x8 pan. Pressing the crust to the bottom and making it flat.
Cook the raspberries, brown sugar, and corn starch to a pan. Cook over medium heat for 5 minutes.
Add the raspberry mixture to the 8x8 pan then sprinkle with chocolate chips and raspberries.
Top the oat bars with the remaining crumb topping.
Bake at 350 degrees for 33 minutes.