Ingredients:

  • 1/2 cup brown sugar, packed
  • 1/3 cup all-purpose flour
  • 1 tablespoon ground cinnamon
  • 3 tablespoons unsalted butter, cold and cubed
  • 2 cups all-purpose flour
  • 3/4 cup granulated sugar
  • 2 teaspoons baking powder
  • 1/2 teaspoon salt
  • 1 large egg, room temperature
  • 1/2 cup full-fat sour cream
  • 1/2 cup whole milk
  • 1/2 cup unsalted butter, melted and cooled
  • 1 tablespoon vanilla extract
  • 1/2 cup powdered sugar
  • 1.5 tablespoons heavy cream
  • 1/4 teaspoon vanilla bean paste

Instructions:

  1. Preheat oven to 375°F (190°C) and line a standard 12-cup muffin tin with paper liners.
  2. Make streusel. Combine 1/2 cup brown sugar, 1/3 cup flour, and 1 tablespoon cinnamon; cut in 3 tablespoons cold cubed butter with a fork until it looks like coarse sand.
  3. Whisk dry. In a large bowl, sift together 2 cups flour, 3/4 cup granulated sugar, 2 teaspoons baking powder, and 1/2 teaspoon salt.
  4. Mix wet. In a separate bowl, whisk 1 egg, 1/2 cup sour cream, 1/2 cup milk, 1/2 cup melted butter, and 1 tablespoon vanilla.
  5. Combine gently. Fold the wet ingredients into the dry ingredients until just combined and no large flour streaks remain.
  6. Fill tins. Divide the batter evenly among the 12 liners, filling them about 2/3 of the way up.
  7. Top generously. Pile the cinnamon streusel on top of each muffin, pressing down very lightly so it sticks.
  8. Bake now. Bake for 18 minutes until a toothpick comes out clean and the tops feel set.
  9. Whisk glaze. Mix 1/2 cup powdered sugar, 1.5 tablespoons heavy cream, and vanilla bean paste until smooth and pourable.
  10. Drizzle warm. Let muffins cool for 5 minutes, then drizzle the glaze over the top until it drips down the sides.