Apple Streusel Muffins

Ingredients:
Batter
2 1/4 cups flour
1 teaspoon baking soda
1/2 teaspoon salt
1 egg
1 cup buttermilk (or 1 teaspoon vinegar and 1 cup of milk)
1/2 cup butter, melted
1 teaspoon vanilla
1 1/2 cups packed brown sugar
2 cups peeled and diced apples
For Streusel Topping
1/2 cup packed brown sugar
1/3 cup flour
1 teaspoon cinnamon
2 tablespoons butter, melted
Directions:
Batter
In a bowl, whisk together flour, baking soda, and salt. In another bowl, whisk together egg, buttermilk, butter, and vanilla. Stir in brown sugar. Add wet and dry ingredients together. Stir just until combined. Don’t over mix. Scoop into muffin tins. Fill about three-quarters full. Sprinkle each muffin with topping. Bake in a preheated oven at 350 degrees for about 15 to 25 minutes. Be careful not to over-bake.
Streusel Topping
Mix all together, until crumbly.