Marbled with a buttery cinnamon ripple, this muffin is much like an individual serving of coffee cake. Need we say more?
Combine all the cinnamon ripple ingredients in a mixing bowl and use an electric mixer to blend them. Set the mixture aside. Then heat the oven to 400° F and grease the bottoms only of 12 standard muffin cups.
Next, make the batter: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. In a large bowl, beat the butter and sugar with an electric mixer until the mixture is pale and fluffy, then beat in the eggs, buttermilk, and vanilla extract. Stir in the dry ingredients just until the batter is blended. Then sprinkle the cinnamon ripple over the batter and use a flexible spatula to fold it in a couple of times.
Divide the batter among the muffin cups and bake the muffins for 13 minutes or until a toothpick inserted into the center of one comes out clean. Let the muffins cool in the pan on a wire rack for 5 to 10 minutes before removing them. Makes 1 dozen.