Mix oats, flour, protein powder, and cinnamon together in a bowl.
Place bananas, milk, eggs, brown sugar, and vanilla extract in a blender; blend until smooth. Slowly add oats mixture to banana mixture while blender is running until batter is smooth.
Heat a skillet or griddle over medium-low heat; add butter. Pour batter over hot butter, about 1/4 cup per pancake; dot with chocolate chips. Cook until pancakes begin to bubble and edges are dry, 3 to 5 minutes. Flip and cook until other side is done, 3 to 5 minutes more.