A Moist Bakery style Double Chocolate Walnut muffins recipe.
Preheat oven to 350F. Line a muffin pan with paper liners to make 12 muffins.
Cream together the butter, sugar, sour cream, and vanilla until light and fluffy - about 3 minutes. Add the eggs, beating until incorporated.
Stir together the flour, baking powder, cocoa powder, and salt.
Add flour mixture to butter mixture alternately with the milk, in 2-3 additions each. Mix until blended, add walnuts.
Divide batter between 12 muffin cups
Bake 25-27 minutes, until toothpick comes out clean