Line two muffins or cupcakes molds of 12 each with cupcake or muffin liners.
In a big bowl, stir together the flour, oatmeal, baking powder, salt, cinnamon, brown sugar, and sugar.
In a different, big bowl, place the mashed bananas and the two eggs and mix using a mixer. Then mix in the milk, oil and vanilla, and keep on mixing.
Add in the flour mixture, little by little, mixing after each addition. Keep on mixing until everything´s well combined.
In a small bowl, place the chopped nuts, and spread some flour on them, making sure every piece is coated, this will avoid the nuts from falling and staying all in the bottom when baking.
Add in the nuts to the mixture, and using a rubber spatula, mix them in.
Pour the batter in the lined muffin cups, filling them to about 3/4 of their capacity.
Bake at 392°F (200°C) for 15 to 25 minutes aprox. or until when inserting a wooden stick, this comes out clean. Let them cool down completely before eating them.