Ingredients    : 

1 cup rolled oats
1 cup all-purpose flour
1 tablespoon rolled oats
1/2 cup chopped walnuts
1 teaspoon baking soda
1 teaspoon baking powder
1/4 teaspoon ground cinnamon
1/2 teaspoon salt
1/2 cup butter, softened
1 cup white sugar
2 eggs
1 cup mashed ripe banana
1 teaspoon vanilla extract
1/2 cup sour cream
1/3 cup rolled oats
4 tablespoons brown sugar
1/4 teaspoon ground cinnamon
2 tablespoons butter, chilled
1/4 cup chopped walnuts

Direction    : 

Prepare the oven by preheating it to 350 ° F (175 ° C) then coat
12 muffin cups with grease or you can line them using paper
liners.

Ground 1 cup of rolled oats in a food processor and then combine
the ground oats with 1 tablespoon rolled oats, flour, baking
powder, chopped walnuts, salt, and cinnamon in a big bowl.

Combine the sugar and butter in a different bowl and cream them
until the mixture is soft and light. Add the eggs one at a time,
beating it in then add the vanilla and banana, stirring them into
the mixture. Add the sour cream, stir it in then pour into the egg
mixture the oat/flour mixture. Scoop batter into each of the
muffin cups.

For the topping, put together 1/3 cup rolled oats, cinnamon, and
brown sugar in a small bowl. Slicing in the butter, adding into the
mixture and mix until the texture is like coarse crumbs then stir in
the 1/4 cup of chopped walnuts. Drizzle the toppings on top of
the muffins generously.

Place the muffin cups in the oven and bake for 25-30 minutes
until the muffins are golden brown or until an inserted toothpick
exits clean.

Nutrition Information      : 

Calories: 340 calories;
Cholesterol: 61
Protein: 5.1
Total Fat: 18.1
Sodium: 319
Total Carbohydrate: 41.4