Cook pasta. Bring a large pot (~5 quarts) of water to a boil. Add salt to the boiling water. Boil 11-13 minutes until al dente. Drain in colander and set aside.
While cooking pasta, prepare the spinach artichoke sauce. In a high-powered blender or food processor, blend together canned cannelini beans, garlic and 1/2 cup of broth. Set aside.
Heat butter or oil in large skillet over medium heat. Add canned artichokes, cooking until lightly browned, about 4-5 minutes. Add spinach and parmesan cheese to the skillet and toss together. Last, add the sauce, mozzarella cheese, and another 1/4 cup of broth. Toss together.
When pasta is done cooking, add it to the skillet. Toss together so pasta and veggies are coated in sauce. Season with black pepper. Sprinkle with additional parmesan and crushed red pepper flakes before serving. Enjoy!
Notes: To re-heat, you can either add to skillet with some extra broth, or bake in an oven-safe dish until warmed.