In a large mixing bowl, combine Bisquick, eggs, milk, and bananas. Using a wire whisk, beat until batter is somewhat smooth but has a few lumps from the bananas.
On a heated griddle or non-stick skillet, spray non-stick cooking spray. Pour just under 1/4 cup of the batter into the skillet. If using a large skillet, you should be able to get 3 to 4 pancakes per batch. Don’t overcrowd the skillet.
Cook until edges are dry and batter starts to bubble a little in the middle. Carefully turn the pancake over using a spatula. Once you have flipped the pancake, take a basting brush and dip into butter. Carefully spread the butter over the pancakes while they are in the skillet.
Serve with sliced bananas, walnuts and warm maple syrup on top.