Preheat the oven to 400 degrees F.
Cut the florets from the core of the cauliflower head.
Bring a pot of water to boil and add the cauliflower.
Boil cauliflower until tender, about 10 minutes.
Drain from the water and then place the steamed cauliflower in a large food processor.
Process until pureed.
Add the cream cheese, garlic powder, and salt, and process until combined, scraping down the edges a couple of times.
Meanwhile, make the filling.
Add the turkey to a large skillet and cook until browned, breaking it into smaller pieces as it cooks.
Once cooked, add the olive oil and onion, and cook until the onion is tender, about 5-7 minutes.
Add the garlic, season with salt and pepper, and cook one more minute.
Add the flour, stirring to combine, and cook one more minute.
Slowly add the broth, stirring well to combine.
Add the Worcestershire, tomato paste, thyme, and rosemary, and stir well to combine.
Stir in the frozen vegetables to combine.
Transfer the filling to a greased 8x8" or 9x9" baking dish.
Top with the cauliflower mash.
Bake in the preheated oven for 20-25 minutes, until the filling is bubbling and the top is starting to become golden.
Serve with fresh thyme. Enjoy!