Blueberry Filled Muffins

1/2 cup butter, softened
1 1/2 cups sugar
4 large eggs
1 tsp. vanilla
3 cups flour
1 tsp. baking powder
1/2 tsp. salt
1/2 tsp. grated lemon zest
1 cup buttermilk
1 cup fresh or frozen, thawed blueberries

Preheat oven to 350 degrees. Grease 12 standard size muffin cups.
To prepare muffins, in a large bowl, using a wooden spoon or an electric mixer set on medium speed, beat together butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla.
In a medium bowl, mix together flour, baking powder and salt.
Using a wooden spoon, stir flour mixture into egg mixture. Fold in lemon zest. Gradually stir in buttermilk until dry ingredients are just moistened. Do not overmix.
Spoon batter into prepared pan, filling 2/3 full. Spoon a heaping tablespoon of blueberries into center of each muffin.
Bake in preheated oven until lightly golden, 18 to 20 minutes. Transfer muffin pan to a wire rack to cool slightly. Remove muffins from pan and serve warm. Makes 12 muffins. Enjoy!