Bring a large pot of salted water to a boil and cook farfalle until al dente according to package instructions. Reserve 0.5 cup of pasta water before draining.

In a large skillet over medium-high heat, cook the ground beef and Italian sausage together, breaking into crumbles, until browned and cooked through. Drain excess fat.

Reduce heat to medium and add butter to the skillet. Once melted, add the minced garlic and sauté for 60 seconds until fragrant.

Pour in the heavy cream and bring to a light simmer. Continue to cook for 4-5 minutes until the sauce begins to thicken slightly.

Whisk in the Parmesan cheese, salt, black pepper, and red pepper flakes until the cheese is completely melted and the sauce is smooth.

Add the fresh baby spinach to the sauce and stir for 1-2 minutes until just wilted.

Incorporate the cooked pasta into the skillet. Toss to coat evenly, adding reserved pasta water in small increments if the sauce requires thinning.

Serve immediately, garnished with additional Parmesan cheese if desired.