Preheat oven to 375 degrees.
Generously butter a standard 12-cup muffin pan and dust with flour, tapping out excess; set aside. You may also line with cupcake wrappers.
In a medium bowl, whisk together flour, baking powder, and salt. Working over the bowl, toss blueberries in a fine sieve with about 1-1/2 teaspoons flour mixture to lightly coat; set aside the flour mixture and the blueberries.
In the bowl of an electric mixer or using a handheld mixer, beat butter and 1 cup sugar on medium-high speed until light and fluffy, about 3 minutes.
Add eggs, one at a time, beating until combined.
Mix in the vanilla extract.
With the mixer on low speed, add reserved flour mixture, beating until just combined. Add milk, beating until just combined. Do not overmix.
Using a rubber spatula, fold in the blueberries.
Divide batter evenly among the prepared muffin cups.
For topping mix together 1/4 cup sugar and nutmeg. Sprinkle sugar mixture on top of muffin batter.
Bake, rotating pan halfway though, until muffins are golden brown and a cake tester inserted in the center of one muffin comes out clean, about 30 minutes.
Transfer pan to a wire rack to cool 10 minutes before serving.
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