Begin by bringing a large pot of salted water to a rolling boil. Add your choice of pasta and cook for 8-10 minutes until al dente. Drain and rinse with cool water, then set aside.

In a large skillet, heat the olive oil over medium-high heat. Add the steak pieces and sear for about 3-4 minutes until browned on all sides. Remove and set aside.

In the same skillet, lower the heat slightly and add the diced onion. Sauté for 2-3 minutes until translucent. Add minced garlic and sauté for an additional 30 seconds.

Reduce the heat to medium-low and pour in the heavy cream. Stir and gradually add the shredded cheeses, allowing them to melt into a smooth sauce. Season with salt, black pepper, and optional red pepper flakes.

Once the sauce is smooth, return the seared steak to the skillet. Stir to coat the steak in the sauce. Add the cooked pasta and mix until thoroughly combined.

Preheat your oven to 375°F (190°C). Transfer the pasta and steak mixture into a greased baking dish. Bake uncovered for 15-20 minutes until golden and bubbly.

Remove from the oven, let rest for a few minutes, and then sprinkle with freshly chopped parsley before serving.