Pat the steaks dry and season generously on all sides with Cajun seasoning. Heat olive oil and butter in a large skillet over medium-high heat. Sear steaks for 3-4 minutes per side for medium-rare. Remove from skillet and let them rest on a cutting board.

While the steak rests, cook pasta according to package directions until al dente. Reserve 1 cup of pasta water before draining.

In the same skillet, reduce heat to medium. Add minced garlic and shallot, and cook until fragrant, about 1 minute.

Pour in the chicken broth to deglaze the pan, scraping up any browned bits. Stir in the heavy cream and drained diced tomatoes. Bring to a simmer and cook for 5-7 minutes to thicken.

Reduce heat to low and stir in the grated Parmesan cheese until melted and smooth. Season the sauce with salt, pepper, and additional Cajun seasoning to your taste.

Slice the rested steak against the grain. Add the drained pasta to the skillet with the sauce, tossing to coat. If needed, add a splash of reserved pasta water to reach the desired consistency. Stir in the sliced steak, garnish with fresh parsley, and serve immediately.