- Set a rack in the middle of the oven and preheat to 375 degrees Fahrenheit/190 degrees Celsius.
- Spray the wells of Stud Muffin with nonstick pan spray.
Make the crumb topping:
- In the medium Stir Crazy bowl, combine the flour, brown sugar, cinnamon, and melted butter.
- Using your fingertips, mix the dry ingredients into the melted butter until irregular, pea-sized clumps form. The mixture should resemble wet sand. Set aside.
Make the blueberry muffin batter:
- In the small Stir Crazy bowl, gently toss the blueberries and 2 tablespoons (16 grams) of the flour together until the berries are evenly coated. Set aside.
- In the large Stir Crazy bowl, whisk together the remaining flour, brown sugar, baking powder, cinnamon, baking soda, and salt.
- In a separate large bowl whisk together the milk, oil, eggs, lemon zest, and vanilla.
- Add the wet ingredients into the dry and stir with a rubber spatula just until a batter forms with no pockets of dry flour remaining.
- Add the blueberries to the batter and gently fold them in to evenly distribute.
- Using a large cookie scoop (or a 1/4-cup measure), portion the dough into the wells of Stud Muffin so they are filled three-fourths of the way to the top.
- Sprinkle the tops with the crumb topping (about 1/4 cup per muffin) and gently press the crumbs in with your hands so they stick.
- Bake until the tops are light golden brown and a toothpick inserted into the center comes out clean, 13 to 16 minutes. Let cool completely.
Make the glaze:
- In a medium bowl combine the confectioners’ sugar and milk.
- Whisk until the sugar is completely dissolved. The glaze should be thick yet pourable. If too thin, whisk in an additional tablespoon of confectioners’ sugar. If too thick, whisk in an additional teaspoon of milk.
- Drizzle the icing over the tops of the cooled muffins and let set for 10 minutes before serving.