Preheat the oven to 350°F (175°C).

In a mixing bowl, mash the ripe banana until smooth.

Add the milk, honey, and vanilla extract to the mashed banana and whisk until well combined.

In a separate bowl, mix the rolled oats, protein powder, baking powder, and cinnamon.

Pour the wet mixture into the dry ingredients and stir until just combined.

If desired, fold in the nuts or chocolate chips.

Pour the mixture into a greased baking dish and spread it evenly.

Bake in the preheated oven for 25 minutes or until golden brown.

Let the baked oats cool for a few minutes, then slice and serve warm.