Cook the Meat Mixture:

• In a skillet over medium heat, heat 2 tsp olive oil.
• Add onion, garlic, ground beef, and ground pork. Season with salt and pepper.
• Cook for about 5 minutes until browned. Remove from heat and let cool.

Cook the Manicotti:

• Bring a large pot of salted water to a boil.
• Cook the manicotti for 6 minutes, then drain and toss with a little olive oil to prevent sticking. Let cool.

Prepare the Filling:

• In a bowl, mix ricotta, 2 cups mozzarella, ½ cup Parmesan, parsley, and nutmeg.
• Stir in the cooled meat mixture until well combined.

Assemble the Manicotti:

• Preheat oven to 350°F (175°C).
• Drizzle 2 tsp olive oil into a 13×9 baking dish. Spread 1 ½ cups marinara sauce over the bottom.
• Fill each manicotti shell using a piping bag (or a Ziploc with the corner cut off) or carefully spoon in the filling.
• Arrange the stuffed pasta in a single layer in the dish. Pour remaining sauce on top.
• Sprinkle remaining 1 ½ cups mozzarella and ½ cup Parmesan cheese over the top. Evenly distribute butter pieces.

Bake:

• Bake uncovered for 30-35 minutes, until bubbly and golden.
• Let rest for 5 minutes before serving.