Bring a large pot of well-salted water to a boil. Add fettuccine and cook until al dente.
Reserve ¾ cup pasta cooking water, then drain pasta.
Meanwhile, when pasta is about halfway done, warm olive oil in a large frying pan over medium heat.
When hot, add tomato paste, garlic, chili paste, and ½ teaspoon kosher salt. Cook, stirring constantly, until tomato paste darkens in color (about 2 minutes).
Mix mascarpone into tomato mixture, stirring until it's fully combined with other ingredients.
Add pasta and reserved pasta cooking water to sauce. Toss together until sauce thickens slightly and coats pasta evenly. Remove from heat, then season to taste with additional salt, if needed.
Serve pasta immediately. Enjoy!
Notes
Don't forget to reserve the pasta cooking water. It's essential to creating the smooth, silky sauce. (Tip: I keep a measuring cup next to the pasta pot, so I have a visual reminder.)If your sauce is ready before the pasta has finished cooking, remove it from the heat until you're ready to proceed with the recipe.I used 1 ½ tablespoons of crushed Calabrian chili peppers, which made the dish spicy, but not overwhelmingly hot (my 12-year old niece ate this pasta with no issues). If you're not sure how much pepper paste to add, start with just a little ... you can always add more.Other long strands of pasta, such as linguine, pappardelle, or spaghetti, will also work well for this recipe.Make sure to check out the info before this recipe card for helpful tips, step by step photos, servings suggestions, and more!