Adjust oven rack to middle position and preheat oven to 375 degrees F. Generously spray 12-cup muffin tin, including top, with baking spray.

In large bowl, stir together topping ingredients until mixture resembles wet sand; set aside.

In separate large bowl, whisk together flour, sugar, baking powder, and salt.

In third bowl, whisk together pumpkin, butter, eggs, milk and vanilla. Stir flour mixture into pumpkin mixture until just combined.

Using greased measuring cup, fill each muffin well with 1/3 cup batter. Sprinkle topping evenly over batter, about 1 tablespoon per muffin.

Bake until golden brown, rotating halfway through cooking time, until toothpick inserted in center comes out with few crumbs attached, about 22 to 25 minutes.

Let muffins cool in tin for 10 minutes. Remove muffins and let cool on rack 5 minutes.