Browned Butter Blueberry Muffins

Source:  Amandeleine
Adapted from Joy the Baker

Muffins

14 Tablespoons unsalted butter
2/3 cup whole milk
2 large eggs
2 large egg yolks
2 teaspoons vanilla extract
3 cups all-purpose flour
3/4 cup sugar
3/4 cup brown sugar
3 teaspoons baking powder
1 1/2 teaspoon salt
4 cups fresh blueberries

Streusel

6 Tablespoons cold, unsalted butter, cut into 1/2-inch cubes
1 cup all-purpose flour
7 tablespoons sugar

Directions

Put a rack in the upper third of the oven and preheat oven to 375 degrees F.  Line two muffin pans with paper or foil liners
Melt butter in a small saucepan over medium heat.  Keep an eye on the butter.  Melt and cook down the butter until little brown bits appear in the pan.  The crackling will subside and butter will begin to brown fairly quickly after that.  Keep a close eye.  Remove from heat.
Whisk milk, egg, yolk and vanilla until combined.  Add the brown butter and stir to combine.
Whisk together flour, sugar, baking powder and salt in a medium bowl  Add milk and butter mixture all at one and stir gently to combine.  Gently but thoroughly fold in the blueberries.
Divide the batter among muffin cups and spread evenly.

Streusel:

Combine all of the ingredients in a bowl and rub together with your fingertips until crumbly.  Sprinkle evenly over the batter in the cups.
Bake until golden and crisp and a wooden pick inserted into the center of a muffin comes out clean, about 18-20 minutes.  Cool in pan on a rack for 15 minutes then remove from the pan.  Serve warm or at room temperature.

Makes 2 dozen regular size or 12 large size muffins (large muffins take longer to bake)