Preheat oven to 450°. Line a rimmed baking sheet with foil. Top with tomatoes, cut side up, garlic, and jalapeño. Roast until tomato softens and jalapeño is beginning to blacken, about 20 minutes.
Meanwhile, cook pasta as package directs. When roasted vegetables are cool enough to handle, finely chop jalapeño, peel, smoosh and chop garlic, and chop tomato. Stir this mixture in a bowl and season with salt and pepper.
Drain pasta and toss with tomato sauce. Plate and top each portion with basil and chives.