Put strawberries in a medium bowl, sprinkle with 5 tbsp. sugar, and set aside to macerate for 30 minutes at room temperature.

Preheat oven to 400°. Sift flour, baking powder, salt, and remaining 1 tbsp. sugar together into a mixing bowl. Cut 4 tbsp. butter into flour mixture with a pastry cutter, or use your fingers to work it in, until mixture resembles coarse meal. Mix in milk. Turn out dough onto a lightly floured surface, knead several times, then shape dough into a large biscuit, 2" thick and 6" in diameter. Bake on an ungreased cookie sheet until just golden, about 15 minutes.

Cool biscuit slightly, then slice it in half horizontally. Spread remaining 2 tbsp. butter on cut sides. Place bottom half of biscuit on a plate and spoon half the strawberries and juice on top. Cover with other half of biscuit and spoon remaining strawberries over top. Serve with whipped cream, if you like.