Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package directions until al dente. Reserve about 1 cup of the pasta water, then drain and set aside.

In a large skillet or sauté pan, heat the olive oil over medium heat. Add the garlic, red pepper flakes, and anchovies. Cook for about 2 minutes, stirring often, until the garlic is fragrant and the anchovies dissolve into the oil.

Stir in the crushed tomatoes, olives, capers, and oregano. Bring the mixture to a gentle simmer and cook uncovered for 10–12 minutes, stirring occasionally. The sauce should thicken slightly and develop deep, rich flavors.

Add the drained pasta directly into the sauce and toss to coat. If the sauce is too thick, stir in a bit of the reserved pasta water (a few tablespoons at a time) until it reaches your desired consistency.

Taste and adjust seasoning with salt and pepper (remember, anchovies, olives, and capers are salty, so you might not need much salt). Sprinkle with fresh parsley and drizzle with a little more olive oil. Serve immediately, with grated Parmesan if desired.