In the bowl of a standing mixer, combine the flour, sugar, baking powder, and salt. Add the cold butter and beat on low, stopping occasionally to break up any large chunks of butter with your fingers, until the mixture resembles fine crumbs.
Beat together the eggs and half and half or whole milk (you can do this in the measuring cup) until lightly combined. Add the egg mixture to the flour mixture and beat until a rough dough forms.
Turn the mixture onto a lightly floured work surface and pat into a rectangle, about ¾ inch thick. Cut into 2-inch rounds with a floured biscuit cutter. Place rounds on a parchment-lined baking sheet, 1 inch apart, and lightly brush with egg wash.
Bake for 12-14 minutes, until lightly browned, rotating the baking sheet 180° halfway through the bake time.
Stir berry mixture together.
For whipped cream, place the cream in the bowl of a standing mixer fitted with a whisk attachment and beat until the soft peaks stage. Add the vanilla and sugar and whisk until medium peak stage.
To assemble: Slice the warm biscuits in half with a serrated knife. Spoon a layer of berries and a layer of whipped cream on one biscuit half. Top with the other half. Spoon a little more whipped cream on the biscuit and top with a strawberry slice. Repeat with remaining biscuits and serve.