Turkey Potpie with a Biscuit Crust

Name: Turkey Potpie with a Biscuit Crust
Ingredients: 2 tablespoons (28 grams) unsalted butter; 2 tablespoons (30 grams) olive oil; 1 red bell pepper, seeded and finely chopped; 1 medium yellow onion, finely chopped; 1 large carrot, finely chopped; 1 clove garlic, minced; 2 cups (290 grams) fresh English peas; 1 cup (165 grams) fresh corn kernels, from about 2 cobs; 1 teaspoon (1 gram) dried thyme; 1/4 cup (30 grams) all-purpose flour; 2 cups (480 milliliters) chicken broth; 1/2 cup (120 milliliters) heavy cream; 2 cups roast turkey meat picked off bone and broken into bite-size pieces; Salt and pepper, to taste; 3 cups (360 grams) all-purpose flour, plus for dusting the work surface; 1 teaspoon (6 grams) salt; 1 tablespoon (11 grams) sugar; 1 tablespoon (15 grams) baking powder; 1/2 cup (100 grams) vegetable shortening, frozen, cut into 1/2-inch cubes; 1/2 cup (100 grams) unsalted butter, chilled, cut into 1/2-inch cubes; 1 cup (240 milliliters) low-fat buttermilk; 1 large egg; 2 teaspoons fresh thyme, minced; Egg wash (1 egg whisked with 2 tablespoons water); Coarse sea salt, for sprinkling