You can substitute up to 1 cup whole-wheat flour or whole-wheat pastry flour for an equal measure of all-purpose flour. Note that the liquid ingredient is infinitely variable, from nonfat or low-fat milk to the richest cream. The flexible amount of butter or oil allows you to control the richness of the muffins with the following advice: Muffins made to be consumed immediately—very fresh and warm from the oven—are perfectly delicious with only 4 tablespoons butter or oil. If muffins must be made hours before they will be consumed, or even the day before, you are wise to use 6 to 8 tablespoons butter or oil.
Position a rack in the center of the oven. Preheat the oven to 400°F. Grease a standard 12-muffin pan or line with paper cups. Whisk together thoroughly in a large bowl:
      2 cups all-purpose flour
      1 tablespoon baking powder
      1/2 teaspoon salt
      1/4 teaspoon ground nutmeg (optional)
Whisk together in another bowl:
      2 large eggs
      1 cup milk or cream
      2/3 cup sugar or packed light brown sugar
      4 to 8 tablespoons warm melted unsalted butter or vegetable oil
      1 teaspoon vanilla
Add to the flour mixture and mix together with a few light strokes just until the dry ingredients are moistened. Do not overmix; the batter should not be smooth. Fold in:
      1 1/2 cups fresh or frozen blueberries
Divide the batter among the muffin cups. Sprinkle the tops with:
      Cinnamon and sugar
Bake until a toothpick inserted in 1 or 2 of the muffins comes out clean, 12 to 15 minutes. Let cool for 2 to 3 minutes before removing from the pan. If not serving hot, let cool on a rack. Serve as soon as possible, preferably within a few hours of baking.