Bring a large pot of salted water to a boil, add cheese tortellini, and cook according to package instructions. Reserve ½ cup pasta water before draining.

Pat steak cubes dry, season with salt and pepper. Heat olive oil in a skillet over medium-high heat and sear steak for 1-2 minutes on each side. Set aside.

In the same skillet, reduce heat to medium, melt butter, and add minced garlic. Stir for about 1 minute. Pour in beef broth or reserved pasta water.

Add cooked tortellini and seared steak to the skillet, stir gently to combine. Sprinkle Parmesan cheese over and stir until melted.

Remove from heat, garnish with parsley and red pepper flakes. Serve immediately.