In a deep skillet, add ground sausage and begin to saute on medium high heat. Halfway through cooking, add sliced onions and minced garlic and continue to cook until sausage is browned and crispy, and onions are caramelized.
Meanwhile, bring a large stockpot of salted water to a boil, and cook pasta to al dente, according to directions; right before draining, reserve ¾ cup of the starchy pasta cooking water, set aside.
When the sausage is crispy and onions are caramelized, deglaze the pan by pouring in the cooking wine, simmer on medium/high-high heat 3 minutes until slightly reduced.
Lower heat to low, add pasta, reserved cooking water, chopped sundried tomato, and parmesan cheese. Toss until melted and smooth. Season with crushed red pepper flake, optional.
Toss, remove from heat, serve immediately with extra parmesan cheese.