Ingredients:

Apple-Nut Muffins
 
1 1/2 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1 teaspoon ground cinnamon
1/2 teaspoon grated nutmeg
2 large eggs
1/2 cup buttermilk, or sour cream
4 tablespoons melted unsalted butter
1 cup packed light brown sugar
1 cup peeled, cored, and chopped sweet apples
1/2 cup chopped walnuts

Streusel Topping:

1/4 cup plus 1 tablespoon finely chopped walnuts
1/4 cup plus 1 tablespoon packed light brown sugar
2 tablespoons all-purpose flour
1/2 teaspoon ground cinnamon
2 tablespoons melted unsalted butter
 
Directions:

Preheat the oven to 375 degrees F. Grease a 12-cup muffin tin and set aside.

Sift together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg into a large bowl. 

In another bowl, whisk together the eggs, buttermilk, and melted butter. Add the sugar and whisk to combine. 

Add to the dry ingredients and mix until just combined. Fold in the apples and walnuts. 

Divide the batter among the muffin tin cups, filling each about 2/3 full.

To make the streusel topping, combine all the ingredients listed above under Streusel Topping in a small bowl, and stir until thoroughly combined and crumbly.

Sprinkle about 1 tablespoon of the crumb mixture over the top of each muffin. 

Bake about 25 minutes or until a tester inserted into a muffin comes out clean. 

Remove from the oven and let sit in the muffin tin for 10 minutes, turn out onto a wire rack and let cool slightly before serving.