In a pan on medium heat, add butter and 1 tablespoon oil. Saute onions for about 12 minutes, until golden and caramelized. Turn the heat off and set aside.
In a separate pan on high heat, cook the bacon until short of being crispy. Add garlic and Thai chilies and cook for another minute. Lower the heat, add onions and peas to the mix.
Cook pasta 1 minute short of al dente. Reserve 1/2 cup of pasta water before draining your pasta. Set aside.
Add pasta to the pan and toss all the ingredients together. Slowly add pasta water while stirring constantly.