Preheat your oven to 425 degrees. Line a muffin pan with paper liners or mist with cooking spray. Set pan aside.
In a small saucepan, melt the butter over medium-low heat, swirling occasionally, until butter turns golden brown. Pour into small bowl and let cool to room temperature.
In a medium bowl, whisk together your dry ingredients: flour, spices, baking soda and salt. Set aside.
In a large bowl, combine the pumpkin, sugar, eggs, vanilla and the golden brown butter. Stir until smooth.
Gradually add the dry ingredients to the pumpkin mixture and stir just until combined.
Divide the batter among the lined muffin cups, filing each cup 3/4 full.
To Make the Streusel
Combine the butter, sugar, flour and cinnamon with a fork or your fingers until all ingredients are evenly combined and crumbly. Sprinkle streusel topping evenly over each unbaked muffin.
Place your muffins in the oven and immediately reduce your heat to 375 degrees. Bake muffins for 20 minutes or until a toothpick inserted in the middle comes out with just a few crumbs. Let cool to room temperature.
To Make the Glaze:
Whisk together the butter, powdered sugar and one tablespoon of the milk until combined and smooth. Add additional tablespoon of milk until the glaze is thin enough to drizzle. Generously drizzle cooled muffins by using a spoon dipped into glaze and swinging it back and forth over the muffin tops.