Preheat oven to 425 degrees, then grease a muffin tin, or line with paper liners. Set aside.
In a large mixing bowl, cream the butter, sugar, and oil until thoroughly combined. Add the eggs, one at a time, mixing until completely incorporated before adding the next. Stir in the vanilla.
In a separate bowl, sift together the flour, baking powder, baking soda, cinnamon, and salt.
Alternate adding the flour mixture and milk to the batter, mixing until just combined.
Using an ice cream scoop or large spoon, distribute the batter between 12 muffin cups.
In a medium bowl, mash together all of the streusel ingredients with a fork until well mixed.
Sprinkle about a tbsp of streusel on the top of each muffin.
Bake muffins for 15-17 minutes or until golden brown. Cool completely.
Combine the glaze ingredients together in a small bowl and whisk until smooth.
Drizzle over muffins. Devour.