Yields about 24 medium muffins.
For the muffins:
12 oz. (24 Tbs.) unsalted butter, warmed to room temperature
1-3/4 cups sugar
4 large eggs
1 lb. 11 oz. (6 cups) all-purpose flour
1 Tbs. plus 2 tsp. baking powder
1/2 tsp. baking soda
1-3/4 tsp. salt
1 tsp. ground nutmeg
1-2/3 cups milk
1/4 cup buttermilk
8 oz. (16 Tbs.) unsalted butter; more as needed
2 cups sugar
2 Tbs. ground cinnamon
Put a rack in the middle of the oven and heat the oven to 350°F. In a stand mixer or a large bowl, cream the butter and sugar. Beat in the eggs, one at a time, until just mixed in. Sift together the flour, baking powder, baking soda, salt, and nutmeg. Combine the milk and buttermilk. With a wooden spoon, mix a quarter of the dry ingredients into the butter mixture. Then mix in a third of the milk mixture. Continue mixing in the remaining dry and wet ingredients alternately, ending with the dry. Mix until well combined and smooth, but don’t overmix. Grease and flour a standard-size muffin tin. Scoop enough batter into each tin so that the top of the batter is even with the rim of the cup, about 1/2 cup. (A #16 ice-cream scoop gives you the perfect amount.) Bake the muffins until firm to the touch, 30 to 35 min.
Melt the butter for the dipping mixture. Combine the sugar and cinnamon. When the muffins are just cool enough to handle, remove them from the tin, dip them into or brush them all over with the melted butter, and then roll them in the cinnamon sugar.
From Fine Cooking 42, pp. 54-55