Add the sliced strawberries to a bowl and toss with the sugar. Set aside for at least 30 minutes so the berries release their juices.
Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a mixing bowl, whisk together the flour, baking powder, and salt.
Cut the cold butter into the flour mixture until it looks like coarse crumbs with small pieces of butter throughout.
Stir in the milk just until a soft dough forms. Avoid overmixing.
Drop spoonfuls of dough onto the prepared baking sheet, spacing them a few inches apart.
Bake for 12–15 minutes, or until the shortcakes are lightly golden and baked through.
While the shortcakes bake, whip the heavy cream with powdered sugar until soft peaks form.
To assemble, split the warm shortcakes in half and layer with strawberries, their juices, and whipped cream. Serve immediately.
