In a bowl, combine ground chicken, egg, breadcrumbs, parmesan, garlic powder, Italian seasoning, salt and pepper. Mix until just combined and roll into ice cream scoop, ball-sized meatballs.
Heat the butter and olive oil in a large oven-safe pan over medium heat. Add the onion and sauté until soft, about 4–5 minutes. Add the garlic and cook for 30 seconds until fragrant. Add the tomato paste and fry off for 2 minutes, stirring often, until it darkens to a deep red.
Pour in the vodka and let it bubble and reduce for a minute, scraping up any browned bits from the base of the pan. Stir through the cream, stock/water, chili flakes, salt and pepper, and stir until combined.
Nestle the raw meatballs into the sauce, spooning sauce over the top. Cover and simmer for 18 minutes turning once, until the meatballs are cooked through.
Preheat the grill/broiler to high.
Top the meatballs with mozzarella, then scatter the breadcrumbs and extra parmesan over the top.
Place under the grill for 3–5 minutes, until the cheese is melted and golden and the breadcrumbs are toasty.
Finish with fresh basil before serving.
