01 -
Heat oven to 375°F. Line a 12-cup muffin tin with paper liners. You'll need a second tin or plan to bake in batches as this makes 15 muffins.
02 -
In a medium bowl, whisk sugar, melted butter, eggs, sour cream, milk, and vanilla until smooth.
03 -
Stir in flour, baking powder, baking soda, and salt just until combined. Don't overmix.
04 -
Mix flour, brown sugar, and cinnamon in a small bowl. Pour in melted butter and mix until you get small clumps.
05 -
Put 2 tablespoons batter in each liner, add 2-3 teaspoons streusel, top with 2 more tablespoons batter, and finish with a sprinkle of streusel.
06 -
Bake for 15-17 minutes until tops spring back when touched. Cool completely on a wire rack.
07 -
Beat cream cheese, butter, and vanilla until creamy. Mix in powdered sugar, then milk until smooth and pourable. Add more milk if needed.
08 -
Drizzle glaze over cooled muffins. Let set before serving.