Prepare all the ingredients for making blueberry banana muffins with oatmeal. You can use leftover oatmeal and frozen berries for this recipe!

In a big bowl, combine flour, sugar, baking powder, and salt by whisking.

In a separate bowl, use a fork to mash the banana.

Combine egg, mashed banana, oatmeal, buttermilk, and oil in a jug.

Pour wet banana muffins mixture into dry, stir to combine.

Carefully incorporate the blueberries into the blueberry banana muffins batter by folding through with a spatula.

Evenly distribute the blueberry banana muffins batter among lined muffin tin wells.

Bake your blueberry banana muffins for 18-20 minutes or until risen, golden and a toothpick tests clean.

Remove the muffins and let them cool on a rack. Serve blueberry banana muffins warm, or toasted with butter.