Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs. Reserve 1/2 cup cooking water, then drain the pasta.
Meanwhile, heat 1 tablespoon olive oil in a large nonstick skillet over medium-high heat. Add half of the eggplant, season with salt and pepper and cook, stirring occasionally, until golden and tender, about 4 minutes; transfer to a plate using a slotted spoon. Repeat with the remaining eggplant, adding another 1 tablespoon oil to the skillet.
Add the remaining 2 tablespoons olive oil and the garlic to the skillet. Reduce the heat to medium and cook, stirring, until the garlic is just golden, about 3 minutes. Add the tomatoes, oregano, 1/2 teaspoon salt and a few grinds of pepper. Cook, stirring occasionally, until the sauce is slightly thickened, about 5 minutes.
Add the pasta, eggplant and the reserved pasta cooking water to the skillet; cook, tossing, 1 minute. Season with salt and pepper. Serve topped with the ricotta and basil. Drizzle with olive oil.