Step 1: Bring a large pot of salted water to a rolling boil. Add the rotini and cook until just al dente according to the package directions. Before draining, scoop out about 1 cup of the pasta water and set it aside for later. Drain the pasta well, drizzle with a touch of olive oil to keep it from sticking, and set aside.

Step 2: While the pasta cooks, pat the steak tips dry with paper towels. This simple step makes all the difference in getting a good sear. Season them generously with Cajun seasoning, smoked paprika, salt, and freshly cracked black pepper.

Step 3: Heat a large skillet over medium-high heat. Add the olive oil and 2 tablespoons of butter. Once the pan is hot and the butter is foaming, place the steak tips in a single layer. Let them sear without moving for 3–4 minutes, then flip and cook another 3–4 minutes until the edges are golden and crisp. Transfer the steak to a plate, cover loosely with foil, and let it rest.

Step 4: Reduce the heat to medium. Melt the remaining butter in the same skillet and stir in the minced garlic. Cook for about a minute until fragrant, scraping up the browned bits from the pan for extra flavor.

Step 5: Slowly pour in the heavy cream and chicken broth, stirring as you go. Add the Dijon mustard and bring the mixture to a gentle simmer.

Step 6: Begin adding the cheddar cheese, a handful at a time, whisking until each addition melts smoothly into the sauce. Stir in the Parmesan cheese until the sauce is creamy and glossy. If the sauce feels too thick, add a splash of the reserved pasta water until it reaches the perfect consistency.

Step 7: Taste and adjust the seasoning with more salt, pepper, or a sprinkle of red pepper flakes for heat. Add the drained rotini and gently toss so the spirals soak up every bit of that rich, cheesy sauce. Let it simmer for another minute or two.

Step 8: To serve, spoon the cheesy rotini onto one side of each plate and arrange the steak tips on the other. Drizzle any extra sauce over the steak, sprinkle with fresh parsley, and serve hot.