In a large pot, cook bacon until crisp. Remove and set aside. Crumble or chop when cooled.
Drain all but 1 to 2 tbsp of bacon grease from pot. Heat remaining bacon fat over medium heat.
Add onion, garlic, squash, and pinch of crushed red pepper. Cook for about 8-10 minutes then add broth. Cook for another 10-15 minutes until squash is tender. Use an immersion blender to puree.
Meanwhile, in another large pot, boil water and cook pasta according to package directions.
Stir the pumpkin into the pureed squash mixture. Gradually add ½ cup reserved pasta water until sauce reaches desired consistency.
Toss pasta in sauce and divide into four servings (approximately 1.5 cups each). Serve topped with crumbled bacon.