Blueberry Coffee Cake (AKA Blueberry Boy Bait)

Name: Blueberry Coffee Cake (AKA Blueberry Boy Bait)
Prep time: 30 min
Cook time: 40 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 6 tablespoons packed light brown sugar; ½ cup all-purpose flour, spooned into measuring cup and leveled-off; 1 teaspoon ground cinnamon; ¼ teaspoon salt; 4 tablespoons unsalted butter, cold, cut into ½-inch chunks; 2 cups all-purpose flour, spooned into measuring cup and leveled-off; 2 teaspoons baking powder; ½ teaspoon salt; 1 stick (½ cup) unsalted butter, softened; ¾ cup granulated sugar; 2 large eggs; 1½ teaspoons vanilla extract; 1 teaspoon packed lemon zest, from 1 lemon; ½ cup milk; 2 cups fresh blueberries (frozen may be used but do not defrost)