For the Cupcakes:
Non-stick baking spray
1 1/4 cups (about 11 1/4 ounces) all-purpose flour
1 teaspoon baking powder
3/4 teaspoon baking soda
3/4 teaspoon salt
1/2 cup buttermilk, at room temperature
1 teaspoon pure vanilla extract
3/4 cup (about 5 1/4 ounces) granulated sugar
1 stick (4 ounces) unsalted butter, at room temperature
2 large eggs, separated and at room temperature

For the Filling:
1 pound fresh strawberries, hulled and sliced from pole to pole
1 tablespoon granulated sugar
2 teaspoons fresh juice from 1 lemon
1/8 teaspoon salt
2 ounces cream cheese, softened
1 1/2 cups heavy or whipping cream, chilled
3/4 cup confectioners’ sugar