We are getting a lot of squash and tomatoes from our CSA and our garden these days. I improvised this for a tasty, quick dinner that uses both. The butter is a bit of an indulgence, but it's essential if you want a thick, tomato base for the stew.
While the pasta is cooking, melt the butter in a large saute pan over medium heat and add the onion. It's important to keep the butter from browning. When the onion begins to turn translucent (after about 2-3 minutes), add the sugar and continue sauteeing the onion, stirring frequently, until it just begins to caramelize (about 5-7 minutes).
Add the bell pepper, garlic and pine nuts and continue cooking over medium heat for another minute or so. Stir frequently to keep the garlic from browning.
Add the squash and white wine, stirring to deglaze the pan and combine the ingredients.
Mix the tomato paste and water until well-combined. After another minute or so, once the squash has begun to "wilt," add the tomatoes, oregano and tomato paste and water mixture, stirring to combine the ingredients and coat them with the tomato paste and water mixture. Season with salt and pepper to taste, cover and cook for an additional 5 minutes.
Stir in the basil just before serving.
Serve over the pasta with a generous topping of Parmesan cheese.