Apple Streusel Muffins

Who doesn't love muffins! These are yummmy.  This came from the Taste of Home Magazine and ended up being a great find.
Makes: 1 doz.

2 c. flour
1 c. sugar
1 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
2 eggs
1/2 c. butter, melted
1 1/4 tsp. vanilla
1 1/2 c. chopped peeled tart apples

Streusel Topping:
1/3 c. packed brown sugar
1 Tblsp. flour
1/8 tsp. cinnamon
1 Tblsp. cold butter

Glaze:
1 1/2 c. powdered sugar
1 to 2 Tblsp. milk
1 tsp. butter, melted
1/4 tsp. vanilla
1/8 tsp. salt

In a bowl, combine the flour, sugar, baking powder, baking soda and salt.  In another bowl, whisk the eggs, butter and vanilla; stir into dry ingredients just until moistened (batter will be stiff).  Fold in apples.
Fill greased or paper-lined muffin cups three-fourths full.  In a small bowl, combine the brown sugar, flour and cinnamon; cut in butter until crumbly.  Sprinkle over batter.
Bake at 375 degrees for 15-20 minutes or until a toothpick comes out clean.  Cool for 5 minutes before removing from pan to a wire rack to cool completely.  Combine glaze ingredients; drizzle over muffins.