To make clam chowder: just use about a cup of chopped clam meat in place of the corn. You could also add some chicken chunks to make chicken corn chowder (you'd want to add them with the potatoes & be sure they got cooked well).
you'll need: 4-6 ears worth of corn kernels fresh farmers' market corn is the best, of course, but frozen corn works fine too. 4-6 potatoes, chopped I generally use russets for their texture, but red ones or purples are fun 1 medium onion, sliced red, yellow, white, shallots, leeks...whatever you got/want! 1 red pepper, diced any color will do 2-6 slices bacon, cooked up & crumbled optional, but you know what they say about fat! (fat = flavor) 6-8 cups stock 4 cups milk 2-4 Tbsp butter or 1/2 - 1 cup roux (recipe below) 1 tsp paprika 1/4 tsp white pepper 1/4 tsp ground cloves 1/4 tsp grated nutmeg 1/8 tsp cardamom salt & pepper to taste around 2 hours (45 minutes solid work time) Serves 6-8. Saute onion in butter until translucent. Add stock & bring to boil. Add potatoes & bring back to boil. Add milk & bring to simmer. Add pepper, corn, bacon & seasonings. Simmer. Add cold roux to hot soup & stir well. Let cool. Roux Recipe: Use equal parts flour & fat. Melt butter or rendered bacon fat (do not brown). Slowly add flour, whisking constantly. Correct consistency (like frosting) with more flour or more butter as needed. Let cool. Only add cool liquids to hot roux (always slowly, always whisking) or cool roux to hot liquids. I usually stir in some half & half to help cool the roux, then add it to the hot soup. Roux will freeze for 2 months.