Heat a large pot of well-salted water to a simmer. Add spaghetti and cook according to package directions, about 8-9 minutes. Drain well, reserving 1/2 cup of pasta water.
Meanwhile, heat olive oil in a large skillet. Add onion and garlic and sauté until soft but not browned, about 3-4 minutes.
Add the white wine and reduce for 2 minutes. Stir in broth, herbs and spices and continue to cook until the liquid has evaporated.
Pour mixture into a blender along with roasted red peppers. Puree until smooth, about 30 seconds.
Pour the sauce back into the pan and whisk in cream. Heat to a simmer and reduce for 1-2 minutes. Add the scallops and cook for about 3 minutes (depending on size) stirring occasionally. Remove from heat and adjust salt to taste. Add the cooked spaghetti and Parmesan cheese tossing to coat in sauce, adding a splash of pasta water if needed.
Divide among serving dishes and garnish with additional Parmesan cheese and fresh basil.