Cinnamon Buttermilk Muffins

7 Tbs. unsalted butter, at room temp
2/3 cup sugar
1 egg
1 1/2 cups all-purpose flour
1 1/2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
1/2 tsp. freshly grated nutmeg (I used 3/4 teaspoon ground Cinnamon)
1/2 cup buttermilk
1 1/2 tsp. vanilla extract

For the Struesel
2 TBS flour 

1/3 cup brown sugar 

1/2 tsp  ground cinnamon

1 TBS  butter, cold

Preheat an oven to 350°F. Grease 9 standard muffin cups with butter or butter-flavored nonstick cooking spray; fill the unused cups one-third full with water to prevent warping.

To make the muffins, in the bowl of an electric mixer fitted with the flat beater, combine the butter and sugar and beat on medium speed until light and fluffy. Add the egg and beat well until pale and smooth.

In another bowl, stir together the flour, baking powder, baking soda, salt and nutmeg. Add to the butter mixture in 2 additions, alternating with the buttermilk and vanilla. Stir just until evenly moistened. The batter will be slightly lumpy.

Spoon the batter into the prepared muffin cups, filling each three-fourths full.

To make the topping, in a small bowl, mix the flour, brown sugar and cinnamon. Cut in butter with a pastry blender or forks until mixture resembles cornmeal. Gently sprinkle topping evenly over batter in prepared muffin tin. Gently press down topping slightly. 

Bake until the muffins are golden, dry and springy to the touch and a toothpick inserted into the center of a muffin comes out clean, 20 to 25 minutes. Transfer the pan to a wire rack and let cool for 5 minutes. Unmold the muffins and let stand until cool enough to handle.
Yield: 10 muffins