Preheat and prep: Heat the oven to 400°F (200°C). Lightly grease a 12-cup muffin tin with cooking spray or oil.
Mix the glaze: In a small bowl, stir together ketchup, brown sugar, vinegar, and Worcestershire.
Set aside.
Combine the wet flavor base: In a large bowl, mix grated onion (and any juices), garlic, eggs, milk, tomato paste, Worcestershire, and Dijon until smooth.
Add dry ingredients and seasonings: Stir in breadcrumbs, salt, pepper, smoked paprika, Italian seasoning, and parsley.
Fold in the turkey: Add the ground turkey and gently mix with a fork or your hands until just combined. Don’t overwork it.
Portion the mixture: Divide evenly among the muffin cups, filling each to the top. Use damp hands or a spoon to smooth the tops.
Top with glaze: Spoon a little glaze over each muffin and spread it to the edges.
Bake: Place the pan on the middle rack and bake for 18–22 minutes, until the internal temperature reaches 165°F (74°C).
Rest and release: Let the muffins rest in the pan for 5 minutes.
Run a thin spatula or knife around the edges to lift them out.
Serve: Add a little extra glaze if you like. Pair with mashed potatoes, roasted veggies, or a simple salad.