In a bowl, combine sliced strawberries and 1/4 cup sugar. Mix well and set aside to macerate (juices will form) while you make the shortcakes.
Preheat your oven to 425°F (220°C). In a large mixing bowl, whisk together flour, sugar, baking powder, and salt. Add the cold butter and cut it into the flour using a pastry cutter or fork until the mixture resembles coarse crumbs.
Stir in milk and vanilla just until the dough comes together. Do not overmix.
Turn dough out onto a lightly floured surface. Gently pat into a 1-inch thick rectangle. Use a biscuit cutter or a glass to cut out 6 rounds. Place on a parchment-lined baking sheet and brush tops with a bit of milk.
Bake for 12–15 minutes or until golden brown. Cool slightly on a wire rack.
In a chilled bowl, beat heavy cream, powdered sugar, and vanilla until soft peaks form.
Slice each shortcake in half horizontally. Layer the bottom with a spoonful of strawberries and their juices, a dollop of whipped cream, then top with the other half of the biscuit. Finish with more whipped cream and strawberries on top if desired.