Divide the batter evenly into the prepared muffin pan, filling all the way to the top. Give the streusel a quick stir, breaking up any large clumps, then evenly sprinkle the streusel on top of each muffin.
Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Let cool in pan for 5 minutes then transfer the muffins to a wire rack to cool completely before glazing.
In a small bowl, whisk the powdered sugar with 1 tbsp at a time of lemon juice until smooth. Drizzle over cooled muffins and enjoy.
1 cup (120g) powdered sugar, 1-2 Tbsp lemon juice
Notes
Leftovers can be stored in an airtight container at room temperature for up to 3 days.