Preheat oven to 350 degrees F. Line a 12-cup standard muffin tin with paper liners; set aside.
To make the streusel topping, combine flour, sugar and cinnamon in a small bowl. Add cold butter and toss to coat, using your fingers to work the butter into the dry ingredients until it resembles coarse crumbs.
In a large bowl, combine flour, sugar, cinnamon, ginger, nutmeg, baking powder, baking soda and salt.
In a large glass measuring cup or another bowl, whisk together pumpkin puree, butter, eggs and vanilla.
Pour mixture over dry ingredients and stir using a rubber spatula just until moist.
Scoop the batter evenly into the muffin tray. Sprinkle with reserved topping, using your fingertips to gently press the crumbs into the batter.
Place into oven and bake for 16-18 minutes, or until a tester inserted in the center comes out clean.
To make the glaze, combine confectioners’ sugar, butter and milk. Whisk until smooth. If the glaze is too thin, add more confectioners’ sugar as needed.
When the muffins are done, cool for 10 minutes and drizzle the glaze on each muffin.