When it comes to clam chowder, I adhere to the milk-based New England school. I say this at the expense of antagonizing the Manhatten school (tomatoe-based), and not because I lived in Boston for three years. To be honest I like both, but I do feel that when you are using fresh clams the acidity of tomatoe will somewhat mask the clean, briny flavors.
The following recipe uses a chowder base adapted from Julia Child, who was alive and living in Cambridge at the time I was a student (I never saw her but often heard stories of sightings):
New England clam "chowdah"
1. Prepare the clams: scrub them under cold water and soak in salted water for at least half an hour so they will spit out the grit and sand. Drain, transfer to a pot and add 2 cups of water. Cover tightly and bring to a boil. They should open within 5 minutes. Discard those that do not. Remove the clams from their shells and chop them coarsely. Strain the pot contents through a sieve and set aside
2. Prepare the chowder base: Cook one chopped onion in 2 tablespoons of butter until soft but not brown. Add 2 waxy potatoes, diced into smallish cubes. Add 2 cups of water (or the reserved clam juice) and simmer until the potatoes are soft, about 20 minutes. Add 2 cups of "half-and-half" or whole milk and cream combined, a bay leaf or two and sea salt to taste.
3. To finish: Add the chopped clams and bring to a simmer (do not boil). Ladle into warmed soup bowls and serve with "oyster" salt crackers.
* To make fish chowder: With the base, gently poach pieces of solid white fish such as halibut. In this case, you might add several slices of bacon cut into strips when cooking the onion and potatoes to strengthen the chowder base. Add blanched snowpeas for color and crunch.