Shepherd’s Potato Pie


For the crust:

1¾ cups all-purpose flour
2 teaspoons granulated sugar
pinch of kosher salt
6 tablespoons unsalted butter, cold and diced
4 tablespoons vegetable shortening
5 to 6 tablespoons ice water

For the filling:

2 tablespoons olive oil
1 pound ground lamb (or ground sirloin or ground turkey)
1 medium yellow onion, diced
3 garlic cloves, minced
2 small carrots, diced
2 celery stalks, diced
1 pound crimini mushrooms, sliced
salt and black pepper
1 teaspoon fresh thyme leaves, plus more for topping
2 teaspoons fresh rosemary leaves, chopped
1 tablespoon tomato paste
1 cup beef stock
2 tablespoons Worcestershire sauce
1 cup frozen peas
1 cup frozen corn kernels
2 tablespoons fresh parsley, chopped
1 large russet potato, thinly sliced into rounds
¼ cup cheddar cheese, shredded