Preheat your oven to 350°F and lightly grease a single-serve baking dish (a small 8-ounce ramekin or 6-inch cake pan works perfectly). Mash the banana until completely smooth—this creates moisture and helps bind the oatmeal together. Measure out all your dry ingredients and have your egg and milk ready to go. This prep work ensures the batter comes together quickly once you start mixing.

Combine the mashed banana, egg, milk, and vanilla extract in a blender or food processor and blend until smooth. Add the oats, cocoa powder, baking soda, and salt, then blend again until you have a cohesive, slightly thick batter with some texture from the oats. I like to use Old Fashioned oats because they maintain a pleasant chewy texture rather than becoming too dense when blended. The blending process ensures even distribution of the cocoa and leavening agents throughout the batter.

Pour the batter from Step 2 into your prepared baking dish, then generously sprinkle chocolate chips over the top—I prefer Ghirardelli semi-sweet because they hold their shape and add a luxurious touch without being overly sweet. Bake for 15 minutes until the top is set but still slightly tender when gently pressed; it should have a brownie-like consistency rather than being completely firm. The baked oatmeal will continue to set slightly as it cools.

Remove the brownie baked oatmeal from the oven and let it cool for just a minute or two. While it's still warm, top with a small pinch of flaky sea salt if desired—the salt adds a wonderful contrast to the rich chocolate and brings out the cocoa flavor beautifully. Serve warm, either in the baking dish or transferred to a bowl, and enjoy immediately.