1. Make the Muffins: Preheat oven to 350 degrees F. Line a standard muffin tin with paper liners; set aside.
2. In a medium bowl, whisk together the flour, baking powder, baking soda, salt and allspice; set aside.
3. In a large bowl, whisk together the buttermilk, oil, brown sugar, egg and vanilla extract until well combined and no lumps of brown sugar remain.
4. Add the flour mixture to the wet ingredients and, using a rubber spatula, fold until mostly combined. Add the chopped apple and fold gently until the apple is evenly distributed and no flour pockets remain.
5. Divide the batter evenly between the muffin cups.
6. Make the Cinnamon-Sugar Crunch Topping: Stir together the melted butter, sugar and cinnamon until thoroughly combined, then spoon evenly over the tops of each muffin.
7. Bake for 15 to 20 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool for 10 minutes in the muffin pan, then remove to a wire rack. Serve warm or at room temperature. Muffins can be stored in an airtight container at room temperature for up to 3 days, or in the freezer for up to 2 months.
Notes
Storing, Freezing, and Thawing Directions
Storing- You can keep these stored in an airtight container for up to 3 days.
Freezing- Wrap the muffins individually to lock in their moisture. Place wrapped muffins in a zip-top freezer bag for up to 2 months.
Thawing- Place the wrapped muffin out at room temperature for about 5 minutes or you can microwave them to warm them up.