Streusel

• 2/3 cup (about 2 7/8 oz.) all-purpose flour
• 1/2 cup packed light brown sugar
• 1/4 cup pecans, finely chopped (about 1 oz.)
• 1 1/2 teaspoons ground cinnamon
• 1/2 teaspoon kosher salt
• 1/4 cup (2 oz.) unsalted butter, melted

Muffins

• 1/2 cup (4 oz.) unsalted butter, softened
• 3/4 cup granulated sugar
• 2 large eggs
• 1 1/2 cups (about 6 3/8 oz.) all-purpose flour
• 2 teaspoons baking powder
• 1 teaspoon kosher salt
• 1/2 cup whole milk
• 1 teaspoon vanilla extract

1. Preheat oven to 350°F. Spray a 12-cup muffin pan with baking spray with flour.
2. Prepare the Streusel: Stir together flour, brown sugar, pecans, cinnamon, and salt in a bowl. Add melted butter; stir until combined and mixture begins to clump. Refrigerate until ready to use.
3. Prepare the Muffins: Beat butter and sugar with an electric mixer on medium speed until fluffy, about 4 minutes. Add eggs, 1 at a time, beating well after each addition and scraping down sides of bowl as needed. Whisk together flour, baking powder, and salt in a medium bowl. With mixer running on low speed, gradually add flour mixture and milk, in alternating batches, to butter mixture, starting and ending with flour and making sure each addition is fully incorporated before adding the next. Stir in vanilla.
4. Pour 1 tablespoon of batter into each muffin cup. Top with 4 teaspoons of streusel. Fill muffin cups with additional 2.5 tablespoons of batter. (You will not use all of the streusel)
5. Bake in preheated oven 10 minutes. Remove from oven, and top muffins evenly with remaining Streusel, pressing gently to adhere. Return to oven, and bake until wooden pick inserted in center comes out clean, 8 to 10 minutes more. Let cool in pan 10 minutes. Transfer to a wire rack to cool completely.