Bring a large pot of water over medium heat to a boil. Salt the water, add the spaghetti and cook to al dente. Remove and reserve a cup or so of the cooking liquid before draining.
Add the tomatoes to a small bowl and season with salt and pepper, to taste. Drizzle with extra-virgin olive oil and sprinkle with oregano. Scatter the tomatoes on a baking rack over a baking sheet and roast about 20 minutes.
Heat about 3 tablespoons extra-virgin olive oil in a large skillet over medium heat. Add the anchovies, working them into oil with a wooden spoon. Stir in the capers, red pepper flakes, garlic, olives, and a splash of olive brine, and saute 3 to 4 minutes, stirring frequently. Stir in the pasta cooking liquid, about 1 cup, and toss in the pasta.
Put the tapenade pasta into serving bowls and top with oven roasted cherry tomatoes. Serve as a first course or alongside a seafood entree.