How to Make It
Combine spinach, basil, cheese, garlic, pepper, kosher salt, and 3 tablespoons of the oil in a mini food processor. Process until mostly smooth, about 10 seconds, stopping to scrape bowl as needed. Set aside.
Cook pasta in a stockpot according to package directions, omitting salt and fat. Reserve 1/2 cup cooking water. Transfer pasta to a colander; drain and rinse with hot water.
Return pot to medium-high heat. Add remaining 1 tablespoon oil and tomatoes; cook, stirring occasionally, until tomatoes start to soften and skins split slightly, 1 to 2 minutes. Add pasta; cook, stirring often, until warmed through, about 1 minute. Remove from heat. Add spinach mixture and 1/4 cup of the pasta water to tomato-pasta mixture; toss gently. Add more pasta water if necessary. Sprinkle with parsley, pumpkin seeds, and flaky sea salt; toss gently. Serve immediately.