Melt butter in a large saucepan over medium heat. Saute onion, garlic, and red pepper. Include jalapeno if desired. Saute until onion is tender.
Add the squash, cilantro, salt and pepper (and bacon if desired), and continue cooking for 5 minutes.
Add broth and simmer for 20 minutes or until chayote is tender.
Use a slotted spoon to removed chayote from broth, and place in blender. Pour enough broth into blender to combine ingredients. Blend into a puree.
Pour into bowls to serve. Garnish with cilantro if desired.
Use olive oil to replace butter, and vegetable broth to replace chicken broth to make recipe vegan.