**Preheat your oven** to 375°F (190°C) and line a muffin tin with paper liners.
In a large bowl or stand mixer, whisk together on medium speed butter, sugar, and lemon zest until pale yellow, and slightly fluffy, 3-4 minutes. Add egg.
In another bowl, whisk together the 1 3/4 c flour, baking powder, salt. (*save 1/4 c flour for next step)
Toss blueberries in 1/4 c flour. *Optional, helps blueberries from sinking to bottom of tin during baking.
Pour the wet ingredients into the dry ingredients, alternating flour mixture and buttermilk and sour cream stir gently until just combined; mixture will be thick but workable. If too dry, add more buttermilk and/or sour cream.
**Fill muffin tin**: Divide the batter evenly among the muffin cups, filling them about 2/3 to 3/4 full.
**Bake** for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow muffins to cool in the pan for about 5 minutes, then transfer them to a wire rack to cool completely.
Mascarpone Cream Cheese Topping
4 oz cream cheese, softened
4 oz mascarpone cheese, softened
1/4 cup powdered sugar
1 teaspoon vanilla extract
1 tablespoon lemon zest
Instructions:
In a medium bowl, beat together the cream cheese and mascarpone until smooth and creamy.
Add the powdered sugar, vanilla extract, and lemon juice and continue to beat until fully combined and fluffy.
**Chill** the topping in the refrigerator until you're ready to use it.
Assemble:
Once the muffins have cooled completely, use a piping bag or a spoon to generously top each muffin with the mascarpone cream cheese topping.
**Garnish** with extra lemon zest or a few fresh blueberries, if desired.
These muffins make for a delightful treat at breakfast, brunch, or any time you crave a sweet and tangy dessert. Enjoy!