How to Make It
Preheat oven to 425°F. Line a large rimmed baking sheet with parchment paper.
Combine flour, sugar, baking powder, kosher salt, and baking soda in bowl of a stand mixer fitted with the paddle attachment. Beat on low speed until combined. Add butter and shortening, and beat on low speed until mixture resembles coarse crumbs and some pea-size pieces of butter remain, about 3 minutes. Beat in buttermilk just until incorporated.
Turn dough out onto a lightly floured surface. Knead and fold dough into thirds, repeating process until it comes together, about 5 times. Dust dough and rolling pin with flour; roll dough into a 3/4-inch-thick (about 12- x 10-inch) rectangle. Cut dough rectangle into 10 (3 1/2-inch) squares. Transfer to prepared baking sheet, arranging dough squares so the edges touch. Brush with cream, and sprinkle with sea salt and black pepper.
Bake in preheated oven until golden brown, about 15 minutes.