For Onions:
Melt butter in a large pot over medium heat. Thinly slice onion and add to the large pot. Season with salt and sugar.
Reduce heat to medium low and cook until onions begin to caramelize. Stir frequently to prevent burning. This will take 15-20 minutes. Remove from heat and allow to cool on a plate.
For Pasta:
Cook pasta according to package instructions. Drain and set aside.
Add sesame oil to the pot and add the garlic. Cook for 1-2 minutes. Add lemon zest. Add pasta and caramelized onions and toss.
Add the chili oil and continue to toss.
Plate and top with a drizzle of chili oil and sprinkle of parmesan cheese.
