In a blender, combine oats and flours and pulse 3-4 times. Add salt, brown sugar, baking powder, egg, vegetable oil, peanut butter, and 1 cup milk. Pulse several times until combined and there are no lumps in the batter.
Preheat a nonstick skillet to medium-low heat and lightly grease with cooking spray. Pour 1/4 cup batter onto the skillet, allow to cook 1-2 minutes until bubbles appear around the edges, then flip and allow to cook another 1-2 minutes until golden. Immediately roll up pancakes and secure with a toothpick. Repeat process with remaining batter.
Serve with raspberry preserves for dipping and pair with remaining 8-ounce glass of milk.
Pancakes can be made ahead - this makes a great on-the-go breakfast or lunch option for little tikes!