2 large eggs plus 2 large egg yolks, beaten to blend
1½ cups plain whole-milk yogurt
½ cup (1 stick) unsalted butter, melted
1 teaspoon finely grated lemon zest
2 teaspoons fresh lemon juice
2 teaspoons vanilla extract
2 tablespoons raw sugar
Preheat oven to 425°. Lightly coat cups of a standard 12-cup muffin pan with nonstick spray. Whisk all-purpose flour, whole wheat flour, granulated sugar, baking powder, salt, and nutmeg in a large bowl to combine. Add 1½ cups blueberries and gently stir until evenly distributed.
Whisk eggs, yogurt, butter, lemon zest, lemon juice, and vanilla in a medium bowl until combined and creamy, about 30 seconds. Gently fold egg mixture into dry ingredients just to combine (be careful not to overmix).
Divide batter evenly among muffin cups. Top with remaining ½ cup blueberries, gently pressing to adhere (you should have 4–5 berries per muffin). Sprinkle with raw sugar.
Bake muffins, rotating pan halfway through, until a tester inserted into the center comes out clean, 25–30 minutes. Transfer pan to a wire rack and let muffins cool in pan 5 minutes. Turn out onto rack and let cool completely.