Preheat the oven to 350°F. Line a cupcake pan with cupcake liners.
In a large bowl, whisk together 1 1/2 cups flour, 1 1/2 teaspoons baking powder, and 1/2 teaspoon salt.
In a large mixing bowl, cream together 1/2 cup butter and 1 cup sugar with an electric mixer for 3 minutes, or until fluffy. Add 2 eggs 1 at a time and mix just until combined. Once mixed, add lemon zest, 3 Tablespoons lemon juice, and 1/2 teaspoon vanilla. Mix until incorporated. Use a rubber spatula to scrape sides of the bowl until batter is well combined.
Slowly add the flour mixture, alternating with 1/2 cup buttermilk. Mix just until combined. With a rubber spatula, gently fold in 3/4 cup blueberries.
Using a large cookie scoop, add batter to the cupcake pan until the tins are about 3/4 full. Bake 18-22 minutes, or until a toothpick inserted in the center comes clean. Let cool completely.
Lemon Frosting
In a stand mixer fitted with the paddle attachment, cream together 1/2 cup butter and 8 ounces cream cheese. Beat until fluffy.
Add 3-4 cups powdered sugar, 2 tablespoons lemon juice, zest, 1 teaspoon vanilla, and salt. Mix until creamy. If you need to thin the frosting, add a dash of milk. If you want to thicken it, add a couple Tablespoons powdered sugar.
Once cupcakes are cooled, pipe or spread the frosting on top of each cupcake.
Top frosted cupcakes with blueberries and lemon zest, if desired.
Notes
Blueberries: If using frozen, do not thaw first. You can also mix the blueberries with a teaspoon of flour to prevent them from sinking. Butter and cream cheese: Make sure to leave both of these out an hour before making or follow these tips on how to soften butter and how to soften cream cheese. Learn how to frost the perfect cupcakes.