Bring a large pot of salted water to a boil. Cook spaghetti for one minute less than package instructions for al dente. Reserve 1/2 cup pasta water, then drain and set aside.

In a skillet, heat olive oil over medium-high heat. Add sliced sausage and cook until golden brown, about 3-4 minutes per side. Remove sausage and set aside.

Reduce heat to medium. Sauté chopped onion for 3-4 minutes until translucent. Add minced garlic and chopped scotch bonnet, cooking for an additional 30 seconds.

Stir in tomato paste, thyme, paprika, and cumin; cook for 1 minute. Add diced tomatoes and broth, season with sugar, salt, and pepper. Simmer and scrape up flavorful bits.

Return sausage to skillet; simmer for 5 minutes. Add spaghetti, toss to coat. Gradually add reserved pasta water to reach desired sauce consistency. Stir in lime juice and fresh herbs.

Serve spaghetti in bowls, garnished with parsley and Parmesan if desired.