Preheat the oven to 375°F and lightly coat an 8-inch square baking dish with cooking spray.
In a large bowl, stir together the rolled oats, baking powder, cinnamon, and sea salt.
Add the non-dairy milk, maple syrup, egg, melted coconut oil, vanilla, and the mashed banana. Stir until combined.
Fold in most of the quartered strawberries and part of the chocolate chips.
Pour the mixture into the prepared baking dish and spread it evenly.
Top with the sliced banana, remaining strawberries, and remaining chocolate chips.
Bake for 35 to 40 minutes, until the center is set and the top is lightly golden.
Rest for 5 to 10 minutes before serving. Serve warm with extra strawberries, bananas, and milk if desired.