Mix the Bisquick, sugar, baking powder and vanilla in a large mixing bowl.
Add milk and stir. Add mashed bananas and stir. Add more or less milk depending on desired pancake thickness. Let the batter sit for a few minutes before cooking.
Meanwhile, heat pan to medium heat and spray with cooking spray or coat with butter or oil. When hot, pour ¼ cup of batter on to the pan, depending on how big you want your pancakes. Cook both sides until a deep golden.
For the syrup, mix syrup and peanut butter together until smooth. I like to thin mine out with 1 tablespoon of milk to get the not-too-thick, not-too-thin consistency I love.