Line a 12-cup muffin tin with liners or coat with cooking spray and preheat the oven to 375°F (190°C).

In a small bowl, whisk together 1/2 cup all-purpose flour, 1/2 cup packed brown sugar, 1 1/2 teaspoons ground cinnamon, and a pinch of salt for the streusel topping.

Add 1/4 cup cold cubed butter to the streusel mixture and use your fingertips or a fork to pinch into coarse crumbs.

In a large bowl, whisk together 2 cups all-purpose flour, 3/4 cup granulated sugar, 2 1/2 teaspoons baking powder, and 1/2 teaspoon salt for the muffin batter.

In a medium bowl, whisk together 1/3 cup melted and cooled butter, 2 large eggs, 3/4 cup whole milk, and 1 1/2 teaspoons vanilla extract until smooth.

Pour the wet ingredients into the dry ingredients and stir gently with a spatula just until no dry streaks remain.

Divide the batter evenly among the muffin cups, filling each about two-thirds full.

Generously sprinkle the streusel topping over each muffin, pressing lightly to adhere.

Bake for 22 minutes or until the streusel is golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.

Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before serving.