Curried Shepherd's Pie

4 -5 medium sized potatoes1 tablespoon olive oil1 large onion, diced1 pound ground beef or turkey4 cloves garlic, minced4 tablespoons hot Madras curry powder2 teaspoons ground tumeric1/4 teaspoon hot pepper flakes1 pound frozen vegetables, thawed (we like the fiesta style mix which includes broccoli, carrots, kidney beans, white beans, garbanzo beans, Italian green beans and red pepper.)butter or