Preheat oven to 350 degrees Fahrenheit.

Line a 12-serving cupcake pan with paper liners. Set aside.

Dry Ingredients: Add flour, baking powder, and lemon zest to a small mixing bowl and whisk to combine. Set aside.

In a large mixing bowl, cream the butter and sugar with an electric mixer.

Next, mix in the eggs until they’re fully incorporated. Then alternate adding the dry ingredients and the milk, vanilla, and lemon juice. Mixing in stages lets everything combine without overmixing. Beat until the batter is smooth.

Spoon the batter evenly into the cupcake liners in a muffin pan until each one is approximately ¾ full.

Bake for 16 minutes, or until a toothpick inserted into one of the cupcakes comes out clean.

Carefully remove the cupcakes from the pan and place them on a wire cooling rack to cool completely.

Add the butter and powdered sugar to a large mixing bowl and mix with an electric mixer until just combined. The mixture will look very dry.

Place the blueberries in a food processor and puree.

Pour the pureed blueberries into the mixing bowl and beat until creamy, scraping down the sides of the mixing bowl with a rubber spatula several times to ensure all ingredients are fully incorporated.

If the buttercream appears too dry, add a small splash of milk and continue to beat well.

Add the buttercream to a large piping bag fitted with a large star tip and pipe a generous swirl of buttercream onto each cupcake.

Garnish with extra blueberries.