Preheat oven to 375 degrees.
Grease an 11x7 inch pan.
Line the bottom of the pan with sliced bananas.
Layer the sliced strawberries over the bananas.
In a small bowl, mix together the oats, walnuts, sugar, baking powder, cinnamon, and salt. Layer the mixture evenly over the strawberries.
In a small bowl, mix together the milk, egg, melted butter, and vanilla. Pour evenly over the oats.
Sprinkle the chocolate over top.
Bake for 35 to 40 minutes, or until the oatmeal has set.
Serve hot. If desired, top with a dollop of greek yogurt with a maraschino cherry on top.