Wet ingredients: Mash the bananas with the milk and vanilla extract in an 8x8" (20x20 cm) baking dish. Alternatively, blend everything in a blender and pour it into the baking dish.
Dry ingredients: Add the oats, cocoa powder, baking powder, and salt to the baking dish. Stir well to combine.
Almonds: Roughly chop the almonds with a knife.
Add-ins: Fold in the almonds, chocolate chips, and raspberries (if using).
Bake for 30 minutes. Use then fan (convection) mode of your oven if it has one.
Let it cool down completely and store in the refrigerator for up to 4 days.
Notes
Serve warm or cold with a splash of milk.
Optionally, top with almond or peanut butter, plant-based yogurt, or maple syrup.
You can store the baked oatmeal for up to 4 days in the refrigerator in an airtight container.