Preheat the oven to 350 degrees F.

Spread oats across a baking sheet and toast for 6 minutes until light brown.

Spray a 9x9 cooking dish with cooking spray and set aside. Reserve ½ cup baked oats and set aside.

Place remaining oats in a food processor and blend until finely ground.

In a medium bowl, whisk together processed oats, flour, baking powder, baking soda, and salt. Set aside.

Using a stand mixer or a hand mixer, beat together softened butter, granulated sugar, and ¼ cup of brown sugar until light and fluffy.

Add eggs 1 at a time, combining well in between, next add the vanilla and mix until incorporated.

Alternate adding the flour mixture and the sour cream into the wet batter, starting and ending with the flour mixture.

Pour batter into the prepared baking pan and spread to smooth out.

Combine remaining baked oats, remaining brown sugar, and cinnamon in a bowl.

Use a pastry cutter until well blended. Sprinkle evenly across the batter.

Bake for 38-42 minutes or until a toothpick comes out clean.