01 -
Preheat the oven to 400°F and line a standard muffin tin with paper liners.
02 -
In a small stainless steel skillet over medium heat, melt the butter. Swirl the pan occasionally and continue cooking until it becomes foamy and begins to crackle. Once the crackling stops, swirl until a nutty aroma develops and brown bits form at the bottom. Remove from heat and pour into a medium mixing bowl, getting all toasted bits. Set aside to cool.
03 -
In a small bowl, combine all topping ingredients. Mix with a fork until the texture resembles wet sand.
04 -
In a large bowl, whisk together flour, sugars, salt, and baking powder. In a medium bowl, whisk cooled browned butter, buttermilk, egg, and vanilla. Pour into the dry ingredients and stir with a rubber spatula until just combined. Fold in the blueberries gently without overmixing. Batter will be thick.
05 -
Divide batter evenly among the muffin tin cups. Use your fingertips to sprinkle the crumb topping over the batter in the cups.
06 -
Bake until golden brown and a toothpick inserted in the center comes out clean, about 20 to 22 minutes. Cool the muffins in the pan on a wire rack for 5 minutes, then transfer muffins to the rack to cool completely.
07 -
Store muffins in an airtight container at room temperature for up to 3 days or freeze for up to 3 months. Reheat in the microwave for about 15 seconds if desired.