In a bowl, combine the sliced strawberries and granulated sugar. Toss gently and let them macerate at room temperature for at least 30 minutes, allowing the juices to release.
Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large mixing bowl, whisk together the flour, baking powder, and salt.
Add the chilled cubed butter and use a pastry cutter or your fingers to work the butter into the flour until the mixture resembles coarse crumbs.
Stir in the milk and vanilla extract until just combined. Be careful not to overmix.
Turn the dough out onto a lightly floured surface and gently knead it a couple of times until smooth. Roll or pat the dough to about 1 inch thick.
Use a round cutter to cut out shortcakes and place them on the prepared baking sheet. Gather any scraps, reroll, and cut out additional shortcakes.
Bake in the preheated oven for 12-15 minutes, or until golden brown. Allow the shortcakes to cool slightly on a wire rack.
While the shortcakes cool, whip the heavy cream and powdered sugar together in a bowl until soft peaks form.
To assemble, slice the shortcakes in half horizontally. Layer a generous spoonful of the macerated strawberries on the bottom half, followed by a dollop of whipped cream. Place the top half back on.
Serve immediately, garnished with a sprig of fresh mint if desired.