Banana Sourdough Muffins

From my mother-in-law's kitchen;

Ingredients
2 cups all-purpose flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1 teaspoon fine sea salt
3 very ripe bananas, about 1 cup mashed
8 tablespoons unsalted butter
1 cup dark brown sugar
2 large eggs
3 tablespoons sour cream
1 teaspoon vanilla extract
1/2 cup sourdough discard
1 cup walnuts, chopped and divided

Instructions
Take pizza brick out of oven. Preheat oven to 250 degrees F and line a 12 count muffin tin with paper liners or lightly grease.

Whisk the 2 c flour, 1 t salt, 2 t baking powder, and 1/2 t baking soda together in a bowl and set aside.

In a separate bowl, use a fork to mash the 3 bananas until smooth.

Melt the 8 T butter in a mixing bowl and add the 1 c brown sugar. Cream the butter and sugar together. Add the bananas, 2 eggs, 3 T sour cream, 1 t vanilla extract, and 1/2 c sourdough discard then mix until combined (hand mixer optional).

Add the wet ingredients to the dry ingredients and mix with the spatula until just combined. Don't over mix! Gently fold in 2/3 cup of the chopped walnuts.

Divide the batter into the muffin tin and sprinkle the remaining 1/3 cup of chopped walnuts on top. Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Transfer to cooling rack.