In a large bowl, combine the strawberries with 1/4 cup (50g) of granulated sugar. Stir well to mix. Cover the bowl and refrigerate. This chilling period allows the strawberries to macerate, enhancing their natural sweetness and forming a syrupy base.
Preheat your oven to 400°F (204°C). In a large bowl or food processor, blend the flour, sugar, baking powder, baking soda, and salt. Mix or pulse until well combined. Incorporate the cold cubed butter, either by cutting it in with a pastry cutter or pulsing several times if using a food processor, until the mixture resembles coarse crumbs.
Transfer the dry ingredients to a large mixing bowl if needed, then pour over the buttermilk. Using a large spoon or a silicone spatula, fold the ingredients together just until they start to form a dough. Be mindful not to overmix; the dough should appear shaggy and slightly crumbly. Turn out the dough onto a generously floured surface. With floured hands, gently press and shape the dough into a rectangle about 3/4 inch thick. Fold the dough in thirds, turn it 90 degrees, and repeat the flattening and folding process two more times.
Using a 2.75 or 3-inch biscuit cutter, cut out rounds from the flattened dough. Press straight down with the cutter without twisting, to help the biscuits rise evenly during baking. Gather any dough scraps, re-roll, and continue cutting until all the dough is used. You should have about 10-12 biscuits.
Place the biscuits in a 10-inch cast iron skillet or on a baking sheet lined with parchment paper or a silicone mat, arranging them so they just touch each other. Brush the tops with the remaining heavy cream or buttermilk and sprinkle with coarse sugar. Bake in the preheated oven for 18-22 minutes, or until the biscuits are golden brown on top. Allow to cool in the pan for at least 10 minutes.
In a mixing bowl, use a hand mixer or a stand mixer with a whisk attachment to beat the heavy cream with the remaining 2 tablespoons of sugar and vanilla extract. Whip on medium-high speed until soft to medium peaks form, which should take about 3 minutes.
Slice each biscuit in half horizontally. Spoon a generous layer of the macerated strawberries over the bottom half of each biscuit, followed by a dollop of whipped cream. Cap with the top half of the biscuit and serve immediately.