Prepare seafood. Keep all ingredients on the ice. Peel and devein shrimp. If using large scallops and shrimp, slice them in half.
Prepare vegetables. Peel and dice onions, garlic, sweet potatoes. Cut corn kernels. Remove the woody part of asparagus, cut the tops and dice the stems.
Have all the liquid ingredients, a spatula, and a whisk ready. Melt butter in a pot over medium heat. Add flour and cook stirring for about a minute.
Add cream to the roux and whisk watching how it becomes thick. Add a cup of stock and keep cooking over medium heat whisking until simmering and thick. Add the rest of the stock gradually, whisking, and bring to simmer.
Meanwhile, melt some butter on a frying pan and saute onions, sweet potatoes, and garlic until soft, for about 2-3 minutes. Transfer to the pot and simmer for 5-7 minutes until potatoes are almost cooked.
Add corn and asparagus to the pot, stir, and cook for another 2-3 minutes, simmering.
Add scallops and shrimp and simmer over low heat intil they are almost cooked, for another 2-3 minutes. Add chopped and whole clams and turn the heat off.
Give your chowder a few minutes to rest off heat. In about 5 minutes, check that whole clams are cooked and fully open. If not, give them a few more minutes. Serve equaly dividing seafood ingredients between 4 bowls.