Martha bakes a batch of muffins studded with fresh blueberries and capped with crunchy sugar and crumb toppings.
Make the crumb topping, if desired: Whisk together flour, brown sugar, salt, and cinnamon in a bowl. Pour in melted butter and toss with a flexible spatula until large crumbs form.
Make the muffins: Preheat oven to 375 degrees. Line standard 12-cup muffin tins with paper liners.
Sift together flour, baking powder, and salt into a bowl.
With an electric mixer on medium speed, cream butter and granulated sugar until fluffy.
Add eggs and vanilla; mix until well combined. Reduce speed to low; alternate adding reserved flour mixture and milk, beginning and ending with flour. Gently fold in berries by hand.
Divide batter evenly among prepared cups; if desired, sprinkle generously with granulated sugar and mace. Alternatively, sprinkle crumb topping evenly over batter in each cup.
Bake until light golden on top, rotating tins halfway through, about 30 minutes. Cool in pan on a wire rack 15 minutes before turning out muffins. Serve warm or at room temperature.