Remove the meat from the lobsters, cut into chunks, then refrigerate until ready to use. Add the shells and any juices that collect to a large stock pot.

Remove the corn kernels from the cob, then refrigerate until ready to use. Add the cobs to the stock pot with the lobster shells, along with the quartered onion, celery stalks, cream sherry, white wine, 3 cups whole milk and 2 cups water. Bring up to a simmer, then turn down to the lowest heat setting and cook for 45 minutes. Don’t let it boil - make sure the liquid stays at a very low simmer. Turn off the heat and let the stock sit while you prepare the rest of the soup. If desired, you can strain the stock at this point and refrigerate up to one day ahead. 

Add the bacon to another large pot or dutch oven over medium-low heat and stir until crisp, about 8 minutes. Remove with a slotted spoon to drain on paper towels, then reserve for serving. 

Add butter to the pot along with the rendered bacon fat, then add the onion and celery. Stir until translucent, about 6 minutes. Add the potatoes, reserved corn kernels, salt and pepper, then stir for 1-2 minutes more.

Strain the stock if you haven't already and add it to the pot (you can strain it right over top if you like). Bring it up to a simmer and let cook until the potatoes are tender, about 20 minutes.

When the potatoes can be easily pierced with a fork, stir in the heavy cream and cream sherry, then simmer for 5 more minutes. Add the reserved lobster meat and chives, then stir to combine. 

Ladle the chowder into bowls, then garnish with reserved bacon and more chives. Serve with crusty bread on the side.

Leftovers will keep refrigerated for up to 5 days, and it tastes even better the next day.