Preheat your oven to 400. Spray a large casserole dish with oil.
Add the potatoes to a large pot of salted water and bring to a boil. Boil for 10 minutes, then add the cauliflower and boil for another 10 minutes.
Drain and move to a large mixing bowl, adding in the milk, butter, parmesan, half of the garlic powder, half of the onion powder, and salt. Blend using a hand mixer until smooth. Set aside.
Meanwhile, heat olive oil in a large skillet over medium heat. Add onions and saute for a few minutes until soft. Add the ground turkey, remaining garlic powder and remaining onion powder and cook until the meat is browned.
Add broth, tomato paste, Worcestershire sauce and rosemary. Simmer on low for about 10 minutes.
Add in the frozen mixed veggies and mix well. Pour the contents of the pan into the casserole dish. Next, add the mashed topping.
Bake for 10 minutes then add the cheddar cheese in an even layer on top. Bake for another 10-15 minutes. Enjoy!
