• Preheat oven to 400°. Line a muffin pan with paper muffin cups or spray with nonstick cooking spray.

Streusel

• 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.

Apples

• Gently toss diced apples with 1/2 teaspoon cinnamon and 1 tablespoon packed dark brown sugar. Set aside.

Muffins

• In a large bowl, whisk together the flour, sugars, baking soda, baking powder, salt, allspice and nutmeg, if using.
• In a small bowl, combine the melted butter, buttermilk, eggs and vanilla. Whisk until the 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 the flour disappears. Gently fold in the apples mixed with cinnamon and brown sugar.
• Divide the muffin batter evenly among the muffin cups, using an ice cream scoop or large spoon. Top each muffin evenly with crumb topping. Gently press the crumbs into the batter. Sprinkle with turbinado or coarse sugar, if desired.
• Bake the muffins for 18-20 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!