01 - Preheat oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper cupcake liners.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed.
03 - In a large mixing bowl, beat the softened butter and granulated sugar together using an electric mixer on medium speed until the mixture turns pale, light, and fluffy.
04 - Add the eggs one at a time, beating well after each addition to ensure full emulsification before adding the next.
05 - Mix in the fresh lemon juice and finely grated lemon zest until evenly combined.
06 - Gradually add the dry ingredient mixture to the wet ingredients, alternating with the whole milk. Begin and end with the dry ingredients, mixing until just combined. Avoid overmixing.
07 - Gently fold the diced fresh strawberries into the batter using a spatula, taking care not to overwork the mixture.
08 - Divide the batter evenly among the prepared cupcake liners, filling each liner approximately two-thirds full.
09 - Bake for 16 to 18 minutes, or until a toothpick inserted into the center of a cupcake emerges clean. Rotate the pan halfway through baking for even results.
10 - Remove the cupcakes from the muffin tin and transfer to a wire cooling rack. Allow to cool completely before frosting.
11 - Beat the softened butter in a mixing bowl until creamy and smooth. Gradually add the sifted powdered sugar, beating on low speed until incorporated, then increase to medium speed. Add the fresh lemon juice, strawberry puree, vanilla extract, and a pinch of salt. Beat until the frosting is light, fluffy, and well combined.
12 - Once the cupcakes are completely cooled, frost each generously with the strawberry lemonade buttercream using a piping bag or spatula. Garnish with small strawberry slices or additional lemon zest if desired.