Slice strawberries and toss with sugar, lemon juice, and vanilla. Let sit for 15 minutes.
In a bowl, combine flour, sugar, baking powder, and salt.
Cut in cold butter until coarse crumbs form.
Whisk buttermilk, egg, and vanilla; stir into dry mixture.
Pat dough and cut shortcakes to ¾-inch thick.
Bake at 425°F for 15–18 minutes until golden.
Beat cream, sugar, and vanilla to soft peaks.
Layer shortcake, strawberries, and whipped cream before serving.