Preheat oven to 350°F. Spray a 12-cup muffin tin or line with paper liners.
In a large bowl, use an electric miter to cream butters and sugars until light and fluffy.
Add eggs, one at a time, beating well after each addition.
Beat in sour cream and vanilla.
In a separate bowl, whisk together flour, baking soda, baking powder and salt.
Add dry ingredients to butter mixture, stirring to combine.
Stir in apples.
Divide between muffin cups, filling cups to the top.
Make streusel:
In a small bowl combine sugars, flour and salt. Add Cinnamon & Brown Sugar Flavored Butter and use a fork to gently combine until mixture starts to clump. Don’t overmix.
Bake it:
Sprinkle streusel over top of muffin batter.
Bake for 20-25 minutes until tops spring back.
Make glaze:
While muffins are baking, combine glaze ingredients.