This delightful recipe is at its best in the fall, when oysters are small and plump and fresh corn is plentiful. The soup base can be made ahead, and at the very last moment the oysters and corn can be added and the soup brought to a hot temperature and served immediately. The cornbread is particularly nice baked in tiny barquettes, miniature muffin tins, or even disposable mini-foil molds. The little barquette molds I used here hold 1 tablespoon of batter, but some molds hold as much as 4 tablespoons. If your molds are larger than mine, adjust the cooking time accordingly.
Make the small cornbreads first: Preheat the oven to 425 degrees. Using ½ tablespoon of the butter, butter 8 to 10 small barquette molds and arrange them on a cookie sheet. Melt the remaining 1-½ tablespoons of butter in a small sturdy skillet; add the leeks. Saute over medium heat approximately 1-½ minutes. Let cool.
Meanwhile, mix flour, cornmeal, salt, sugar, and baking powder in a bowl. Add the egg, milk, and finally the sauteed leeks. Stir well, and spoon 1 to 2 tablespoons (depending on the size of the molds) of the cornbread mixture into each mold. Bake the molds on the cookie sheet 10 to 12 minutes, until cornbreads are set and nicely browned.
Remove and discard any pieces of shell from the shucked oysters, and return them to the reserved liquid. Heat the butter in a sturdy kettle, add the leek and onion, and saute gently over medium heat 3 to 4 minutes. Add the garlic, stir for 20 to 30 seconds, and add the milk and cream. Bring to a strong boil, then add the corn, oysters and their liquid, salt to taste, and pepper, and heat until the temperature reaches 170 to 180 degrees at the most. If any scum rises to the surface, remove it with a skimmer. Add the chives and mix well.
To serve: Ladle the chowder into warm bowls and serve immediately with the small cornbreads.