Meanwhile, heat a large drizzle of olive oil in a large pan over mediumhigh heat. Add onion, basil stems, and remaining Tuscan Heat Spice. Cook, stirring occasionally, until onion is softened, 3-5 minutes. Stir in crushed tomatoes, ½ tsp sugar (1 tsp for 4 servings), and ¼ cup plain water (½ cup for 4). Season generously with salt and pepper. Bring to a simmer, then reduce heat to low. Continue to cook until pasta is ready, then scoop out and reserve ½ cup sauce (1 cup for 4).