Preheat the oven to 400 degrees F. Line a muffin pan with paper muffin cups or spray with nonstick cooking spray. Set aside.
To make the crumb topping, combine the flour, sugars, cinnamon, and melted butter in a small bowl. Mix with a fork until combined and mixture is crumbly. Place the bowl in the refrigerator until ready to use.
To make the muffins: In a large bowl, whisk together the flour, sugars, baking soda, baking powder, salt, and allspice. If there are small brown sugar clumps, break them up with your fingers.
In a small bowl, combine the melted butter, buttermilk, eggs, and vanilla. Whisk until eggs are well combined with the other liquid ingredients.
Pour the liquid ingredients over the dry ingredients and gently stir together with a spatula. Don’t over mix the batter, stir just until flour disappears. Gently fold in the apples.
Divide the muffin batter evenly among the muffin cups. Top each muffin evenly with crumb topping. Gently press the crumbs into the batter.
Bake the muffins for 18 to 20 minutes or until the muffin tops are golden and the tops are set. You can insert a toothpick into the center of a muffin and if it comes out clean, they are done.
Transfer the pan to a cooling rack and let the muffins cool for 5 minutes in the pan. Remove from the pan and enjoy!