Easy Chocolate Banana Oat Mug Cake

Whenever I want something chocolatey but do not feel like baking a whole cake, this chocolate banana oat mug cake is one of the easiest treats to make. It is soft, rich, naturally sweetened with ripe banana, and ready in just a few minutes.

Made with simple ingredients like banana, cocoa powder, oat flour, and one egg, this single-serving mug cake is perfect for a quick breakfast, afternoon snack, or easy dessert. You can prepare it in the microwave or use the air fryer for a slightly firmer outside and a soft, moist center.

Prep Time: 3 minutes
Cook Time: 1½–2 minutes
Total Time: About 5 minutes
Yield: 1 serving

Ingredients

1 medium ripe banana
1 large egg
2 tablespoons unsweetened cocoa powder
1 tablespoon oat flour
½ teaspoon baking powder
1 tablespoon dark chocolate chips, optional
3 or 4 thin banana slices for the topping, optional

Instructions

1. Peel the banana and place it in a small bowl or on a plate. Reserve 3 or 4 thin slices for the topping, if desired. Mash the remaining banana thoroughly with a fork until mostly smooth. A few small banana pieces are fine, but try to remove any large lumps so the batter cooks evenly.

2. Add the oat flour, cocoa powder, and baking powder to the mashed banana. Stir well until the cocoa powder is fully incorporated and no dry pockets remain.

3. Add the egg and stir vigorously with a fork until the batter is smooth and all the ingredients are completely combined. The batter will be soft and slightly loose, but it will firm up as it cooks.

4. Lightly grease a microwave-safe mug or small ramekin. Pour in the batter, making sure there is enough room at the top for the cake to rise as it cooks. Smooth the surface with the back of a spoon.

5. Sprinkle the chocolate chips over the batter and arrange the reserved banana slices on top. You can also gently press a few chocolate chips into the batter for small pockets of melted chocolate throughout the cake.

6. Microwave on high for approximately 1½ minutes. Check the center and, if needed, continue cooking in 10-second intervals until the top looks set but the middle is still soft and moist. Avoid overcooking, as the mug cake will continue to firm up slightly while it rests.

7. Allow the mug cake to rest for 1–2 minutes before eating, as the mug and cake will be very hot.

Enjoy it directly from the mug or carefully transfer it to a small plate.

Air Fryer Method

Pour the batter into a lightly greased, air fryer-safe ramekin. Cook at 350°F for 8–9 minutes, or until the outside is set and the center remains soft. For a firmer cake, cook for an additional 1–2 minutes. Allow it to rest for 1–2 minutes before serving.

Make It Your Own

One of the things I love about this chocolate banana mug cake is how easy it is to adjust depending on what I have in the kitchen. You can add a spoonful of peanut butter, almond butter, or hazelnut spread to the center for an extra creamy filling.

Chopped walnuts, pecans, shredded coconut, or a pinch of cinnamon also work beautifully with the banana and chocolate flavors. For a sweeter cake, add a small drizzle of honey or maple syrup. When the banana is very ripe, however, I usually find that it provides enough natural sweetness on its own.

For a no-added-sugar version, leave out the chocolate chips or use no-added-sugar chocolate chips.

Helpful Tips

Use a very ripe banana for the sweetest flavor and softest texture. Since microwave power can vary, check the cake after 1½ minutes and cook in short intervals if needed. Choose a large mug to prevent overflowing, and avoid overcooking so the center stays soft and moist.

You can also make oat flour by blending rolled oats until finely ground. For a gluten-free version, use certified gluten-free oat flour.

This easy chocolate banana oat mug cake is warm, soft, and perfect when you want a quick homemade treat.

Enjoy!