1. Preheat oven to 190°C (375°F). Line a baking sheet with parchment paper.

2. In a large bowl, combine ground beef and pork, chopped basil, salt, and pepper. Mix lightly with your hands.

3. In a small bowl, whisk together eggs and milk. Pour over the meat mixture and fold in gently.

4. Add Parmesan, breadcrumbs, and mix until just combined. Do not overwork.

5. Scoop and roll meat mixture into 3.8 cm (1.5 inch) balls—about 20 to 25.

6. Place meatballs on baking sheet, leaving 2.5 cm (1 inch) between each.

7. Press a small piece of butter into the top of each meatball.

8. Bake for 18 to 20 minutes, or until meatballs are firm and cooked through.

9. While baking, warm tomato sauce in a large saucepan over medium heat.

10. Transfer baked meatballs to the sauce and simmer for 5 minutes to absorb flavor.

11. Serve over cooked pasta, topped with a handful of fresh spinach and a squeeze of lemon juice, if desired.