Boil the Pasta: Bring a large pot of heavily salted water to a boil. Add the pasta and cook for 1-2 minutes less than the package instructions (aiming for"al dente"). Reserve 1/2 cup of pasta water before draining.
Crisp the Capers: While the water heats, add 1 tablespoon of olive oil to a large skillet over medium-high heat. Add the capers and fry for 2-3 minutes until they pop and get slightly crisp. Remove them with a slotted spoon and set aside for garnish.
Build the Base: Lower the heat to medium and add the remaining olive oil to the same skillet. Add the sliced garlic, minced shallots, and anchovies (with their oil). Cook for 3-4 minutes, stirring and breaking up the anchovies with a wooden spoon until they melt into a paste, and the aromatics are fragrant but not browned.
Bloom the Spices & Paste: Stir in the ground chili peppers and EVO, then add the tomato paste. Cook for 1-2 minutes until the paste turns a deep brick red and the oil is stained orange.
Simmer the Sauce: Pour in the San Marzano diced tomatoes and the Leccino olives. Season with a pinch of black pepper (be careful with salt, as the olives and anchovies are very salty). Simmer for 10-12 minutes to let the flavors meld and the sauce thicken slightly.
The Finish: Add the drained pasta and the flaked tuna to the skillet. Toss gently to coat, adding a splash of the reserved pasta water if the sauce feels too thick.
Serve: Stir in the fresh parsley. Divide into bowls and top with the reserved, crispy-fried capers and an extra dollop of ground chili if you want more heat.