Hidden Apple Butter Muffins

Description
This recipe came from an estate sale. I obtained it when I purchased the family collection from the Hager Estate in Canton, Texas in 1982.
 * Contributed by Catsrecipes Y-Group

Ingredients

 * 1½ cups all purpose flour
 * 1 cup light brown sugar
 * ½ cup butter
 * 1 teaspoon ground cinnamon
 * 2 teaspoons baking powder
 * 2 eggs separated
 * 1 tablespoon apple cider vinegar
 * 1 teaspoon baking soda
 * ⅓ cup milk
 * ⅔ cup apple butter

Directions

 * 1) Preheat oven to 400°F.
 * 2) Grease a muffin tin or tins.
 * 3) In a large bowl mix flour, sugar, butter and cinnamon to a coarse meal or streusel- like crumb.
 * 4) Measure out 1 cup the crumbs and set it aside for the topping.
 * 5) Stir the baking powder into the remaining mixture.
 * 6) Beat the egg whites until they are stiff but still glossy.
 * 7) Combine the vinegar and baking soda.
 * 8) When the bubbles settle down stir in the egg yolks and milk.
 * 9) Pour this liquid and the beaten egg whites over the dry ingredients and immediately combine the batter with a 15 second stirring and folding.
 * 10) Do not expect a smooth thoroughly moistened dough there will be lumps of flour and slicks of egg white showing.
 * 11) Quickly spoon the mixture into the tins.
 * 12) Place a tablespoon of apple butter in the center of each muffin then divide and sprinkle the reserved streusel crumbs over the top.
 * 13) Bake for 20 minutes.
 * 14) Cook for 5 minutes before turning out of tins.