In a large pot, heat the oil over medium-high heat.
Pop the anchovies and grape tomatoes into the pot and let them simmer for 5 minutes or until the grape tomatoes start to soften up and burst. Then add the garlic and chili flakes, and simmer for another minute.
Add the tomato paste to the pot and season with salt and pepper; stir until well combined.
Transfer the crushed tomatoes and their juices to the pot, stir in a pinch of sugar, then add the basil, olives, and capers. Give everything a good stir to combine.
Heat the sauce until it reaches a strong simmer, then decrease the heat to low and let the sauce simmer for about 30 minutes, stirring occasionally. The sauce will reduce and thicken up.
Prior to serving, give the sauce a taste and season it with more salt if necessary.
Add the butter and stir until it melts.
Serve the sauce over noodles of your choice. We like using fettuccine, linguine, or pappardelle!
Garnish with fresh chopped parsley and grated Parmesan cheese.