Instructions

• Preheat the oven to 375°F (190°C). Line a 24-cup mini muffin pan or a 12-cup regular muffin pan with paper liners.
• In a large bowl, beat 1 stick (8 tablespoons) salted butter, 1/2 cup granulated sugar, and 1 tablespoon lemon zest until combined and slightly fluffy.
• Add 1/2 cup plain Greek yogurt and 1 tablespoon vanilla extract to the butter mixture and beat until smooth. Add the 3 room-temperature eggs one at a time, beating until each egg is incorporated before adding the next.
• Measure out 1 tablespoon of the white whole wheat flour and toss it with the 1 cup fresh or frozen blueberries; set the coated blueberries aside.
• In a separate bowl, whisk together the remaining 1 1/2 cups white whole wheat flour, 2 teaspoons baking powder, and 1/2 teaspoon salt.
• Add the dry ingredients to the wet ingredients and mix until just combined. Gently fold in the floured blueberries.
• Spoon the batter into the prepared muffin cups, filling each cup most of the way full. Drop small spoonfuls of the 3 tablespoons blueberry jam over the batter in each cup and use a skewer or knife to gently swirl the jam into the batter—do not overmix.
• (Optional) To make the cinnamon-sugar topping: in a small bowl combine 1/2 cup granulated sugar and 2 teaspoons cinnamon, then stir in 2 tablespoons melted butter until the mixture is moistened. Sprinkle the cinnamon-sugar mixture evenly over the tops of the muffins.
• Bake mini muffins for 18–22 minutes or regular muffins for 28–32 minutes, until tops are set and a toothpick inserted near the center comes out clean or with a few moist crumbs.
• Let the muffins cool in the pan for about 5 minutes, then transfer to a wire rack to cool completely.