Preheat oven to 350°F. Line 2 baking sheets with parchment paper or spray with cooking spray.
In a large bowl, gently combine turkey, chopped onions, egg, milk, 1/2 cup ketchup, 2 Tbsp. Worcestershire, Parmesan, breadcrumbs, garlic powder, salt and pepper. (It’s easiest to use your hands, but you may also use a fork.)
Form mixture into 16 balls and arrange evenly on prepared pan.
In a small bowl, whisk together 1 ½ cups ketchup, 2 Tbsp. mustard and 6 Tbsp. Worcestershire.
Place half of mixture in a separate bowl and set aside (this avoids cross contaminating the mixture.)
Generously brush remaining sauce on meatballs.
Bake for 20-25 minutes until brown and cooked through. (A meat thermometer should read 160 – 165°F)
Prepare Roasted Garlic Mashed Cauliflower as directed on pack.
Divide evenly between eight serving plates and top each plate with 2 meatballs.
Sprinkle with parsley and serve with reserved sauce.