Preheat oven to 350 degrees Fahrenheit and line cupcake tin with liners. Set aside.
Combine ½ cup butter and 1 cup of sugar on medium speed for 2 - 3 minutes until creamed.
Add in 2 eggs, 1 tablespoon lemon zest, ¾ cup lemon juice and 2 teaspoon vanilla. Min until well combined.
Add in ½ teaspoon salt, 1 ½ teaspoon baking powder and 1 ½ cup flour. Mix on low, scraping sides as needed until well combined.
Gently fold in 1 cup of blueberries.
Fill the cupcake liners about ⅔ of the way full with batter.
Bake at 350 for 14 - 16 minutes or until center is set.
Combine 1 cup butter, 1 teaspoon salt, 1 teaspoon vanilla, 2 cups Powdered sugar, 3 tablespoon lemon juice. Mix on low until well combined.
Add remaining 2 cups powdered sugar and mix on low until well combined.
Bump speed to medium and whip another 2 minutes until frosting is smooth and fluffy.
Transfer frosting to a piping bag fitted with a large star tip.
Pipe a large mound of frosting on each cupcake.
Decorate each with a few blueberries and additional lemon zest (if desired).
Notes
Tips + Storage
They are done baking when center is set (you can insert a fork or toothpick and pull it out with nothing sticking to it.
Make sure the buttercream is the right consistency. It should not wilt when scooped up. Too thick - add more lemon juice; too thin - add more powdered sugar.
Make sure cupcakes are cooled before adding frosting
Keep in the fridge in an airtight container for 3 - 5 days or freeze up to a year.