01 -
Heat your oven to 425°F and position a rack in the center. Cover a large baking sheet with parchment paper to prevent sticking.
02 -
In a spacious mixing bowl, combine flour, cornstarch, baking powder, baking soda, granulated sugar, and salt. Whisk everything together until well blended.
03 -
Drop the chilled butter pieces into your flour mixture. Using your fingertips, work the butter into the dry ingredients by rubbing and pinching until you get a crumbly texture with some pea-sized butter chunks scattered throughout.
04 -
Pour in the cold buttermilk and gently stir with a rubber spatula until a rough, sticky dough forms. Don't worry about making it smooth - lumpy is perfect here.
05 -
With lightly floured hands, divide the dough into 8 portions and shape them into rustic balls. Place them on your prepared baking sheet, dust the tops with turbinado sugar, and bake for 13-15 minutes until they're beautifully golden.
06 -
Take about a third of your sliced strawberries and mash them up in a bowl until chunky. Mix in the remaining whole berry slices, raspberry jam, and sugar. Let this sweet mixture sit for 10 minutes to develop its natural juices.
07 -
Using an electric mixer with whisk attachment, beat the heavy cream until it starts to thicken and form soft peaks. Add the sugar and continue beating just until soft peaks return - be careful not to overdo it.
08 -
Carefully slice each warm biscuit in half horizontally using a serrated knife. Place the bottom halves on individual dessert plates, spoon most of the strawberry mixture over them, add a generous dollop of whipped cream, then crown with the biscuit tops. Finish with more berries and cream, and serve right away.