Begin by heating 2 tbsp olive oil in a medium pan and add the sausage until cooked through. Slice into small pieces OR you can remove the sausage from the casing for a ground effect. Once cooked through remove from heat and place in covered bowl.
Next dice the yellow onion into small pieces, followed by dicing the honey crisp apples – leaving skin on. Add 1/2 stick butter to a large pan and allow to melt. Add the diced yellow onion and apples to a sauce pan and begin to sauté until onions are light brown and caramelized. Stir continuously to prevent sticking to pan. Add dried thyme, salt, pepper and red chili flakes. Cook for about 30-35 minutes or until apples are soft and onions are caramelized.
In a large pot, bring water to a boil – adding a pinch of salt to the water. Add the pasta noodles and cook for about 4-6 minutes. Drain the pasta and set aside, keeping about 1/4 cup water leftover.
When the onions and apples are ready, add the garlic and pine nuts and cook until fragrant (about one minute). Add 1 cup dry white wine and cook until the wine is completely evaporated.
Combine the sausage, onion and apple mixture to the pasta as well as 1/4 cup of the reserved pasta water. Make sure to scrape all juices into the pot. Then, toss in the tomato slices and garnish with parmesan. Serve immediately and enjoy!