In a mixing bowl, combine masa harina, salt, garlic powder, and ground cumin. Slowly add hot water while stirring until a soft dough forms. Stir in olive oil and knead gently until smooth. Set aside.
Heat a skillet over medium heat. Add ground beef or turkey, breaking it apart with a spatula. Cook until browned and no longer pink, about 6-8 minutes. Drain excess fat if needed.
Add granulated onion powder, garlic powder, cumin, chili powder, salt, and pepper to the meat. Stir well. Sprinkle cornstarch over meat and stir in. Add drained beans and canned diced tomatoes with green chilies. Cook 3-4 minutes until thickened.
Preheat oven to 375°F (190°C). Press two-thirds of masa dough evenly into bottom and sides of pie dish to form crust. Spoon meat and bean filling evenly over crust. Crumble or press remaining masa dough over filling to create top crust.
Bake pie for 25 minutes or until crust is firm and slightly golden. Remove from oven, sprinkle shredded cheese evenly over top, and return to oven. Bake 5-7 minutes until cheese melts and bubbles.
Let pie cool for 5 minutes before slicing. Serve with favorite taco toppings like sour cream, cilantro, avocado, or salsa.