How to Make It
In a small saucepan, cook the strawberries with the sugar and lemon juice over moderate heat until the berries break down and the juices thicken, about 12 minutes. Let cool completely.
Preheat the oven to 350°. Line 2 rimmed baking sheets with parchment paper. In a medium bowl, whisk the flour with the sugar, baking powder, baking soda and salt. Using a pastry cutter or 2 knives, cut the butter into the dry ingredients until pea-size pieces form. In another medium bowl, whisk the crème fraîche with the egg, buttermilk and vanilla. Stir the crème fraîche mixture into the dry ingredients until a dough just comes together. Fold in the diced strawberries, being careful not to overmix.
Scoop twelve 1/4-cup mounds of the biscuit dough onto the prepared baking sheets, about 3 inches apart. Bake the biscuits for about 30 minutes, until browned; shift the pans from top to bottom and front to back halfway through baking. Transfer the biscuits to a rack and let cool slightly.
In a large bowl, using a hand mixer, whip the crème fraîche with the cream, sugar, vanilla and salt at moderate speed until medium peaks form. Fold in the cooled strawberry swirl until just combined. Serve with the warm biscuits.