Preheat oven to 375 degrees F. Line a 12-cup muffin tin with paper liners. Coat with cooking spray.Advertisement
Whisk flour, cinnamon, baking powder, baking soda and salt in a large bowl. Whisk eggs, buttermilk, brown sugar and vanilla in a medium bowl until smooth. Pour the buttermilk mixture into the flour mixture; fold gently until just combined. Stir in butter until well incorporated. Fold in apples.
Scoop about 1/3 cup batter into each prepared muffin cup. Sprinkle evenly with granulated sugar. Bake until the muffins are puffed and a wooden pick inserted in the center comes out clean, about 20 minutes. Let cool for about 20 minutes.
To make ahead: Wrap airtight and refrigerate for up to 2 days or freeze for up to 3 months.
1 1/2 fat, 1 other carbohydrate, 1 starch