Season the steak cubes with salt and black pepper. In a large skillet, heat olive oil over medium-high heat. Add the steak cubes and sear for about 3-4 minutes, turning occasionally, until browned and cooked to your desired doneness. Remove the steak from the skillet and set aside.

In the same skillet, lower the heat to medium and add the butter. Once melted, add the minced garlic, thyme, and red pepper flakes. Sauté for about 1-2 minutes until fragrant, being careful not to burn the garlic.

Meanwhile, cook the rigatoni according to package instructions until al dente. Drain and set aside.

Add the cooked steak back to the skillet with the garlic butter mixture. Stir to coat the steak in the garlic butter and let it cook for another minute.

In a separate saucepan, combine the heavy cream, mozzarella cheese, and Parmesan cheese over medium heat. Stir until the cheeses are melted and the sauce is smooth. Season with salt and pepper to taste.

Add the drained rigatoni to the cheese sauce, stirring to coat the pasta evenly.

Serve the cheesy rigatoni topped with the garlic butter steak tips. Garnish with chopped parsley.