In a medium bowl, combine the sliced strawberries with ⅓ cup granulated sugar. Stir gently and set aside to macerate for at least 30 minutes, allowing the juices to release.

Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper. In a large bowl, whisk together the flour, ¼ cup granulated sugar, baking powder, and salt. Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs.

Pour in the milk or buttermilk and stir with a fork until just combined; do not overmix. Turn the dough out onto a lightly floured surface and gently knead a few times until it comes together. Pat the dough to about ¾-inch thickness and cut out biscuits with a 2.5-inch round cutter, placing them on the prepared baking sheet. For a golden-brown top, brush the biscuits with a little milk or cream and sprinkle with extra sugar. Bake for 12-15 minutes, or until golden brown.

While the biscuits are baking, prepare the whipped cream. In a large, chilled bowl, beat the heavy cream, powdered sugar, and vanilla extract with an electric mixer on high speed until stiff peaks form.

To assemble, split a warm biscuit in half. Spoon a generous amount of the macerated strawberries and their juice over the bottom half. Top with a large dollop of whipped cream, then place the other biscuit half on top. Add more cream and strawberries if desired.