Cream of Crab soup

So most of my entries are healthy things I make regularly for dinner. This one is not. This is a terribly unhealthy and utterly delicious soup that my husband requests every year for his birthday. It's only once a year, though, so I just consider it a special treat, close my eyes, take a Lactaid, and enjoy.

Mats - serves 4
1 lb can backfin blue crab meat. If you can get it fresh, good on you. Make sure you pick through it well to remove any bits of shell or cartilage.
1 yellow onion
4 Tbsp (1/2 stick) butter
1/3 c flour
2 c light cream or half and half
2 c milk
1 Tbsp Old Bay
4 Tbsp sherry (optional)

In a medium pot, melt the butter over medium low heat
Dice the onion and add it to the melted butter. Cook over medium low heat for 5 minutes, or until the onion begins to soften and turn translucent. You DON'T want to brown it.
Add the Old Bay and flour. Whisk very well until you have a thick paste, no loose butter or lumps of flour
Slowly add the cream and milk, stirring well
Bring to almost a boil - you should just start to hear bubbles form at the bottom of the pot. If they start rising to the surface, your heat's too high.
Add the crabmeat, stir well and cook on medium low for 15 minutes, stirring often. DON'T let it boil.
Divide into bowls, drizzle a tablespoon of sherry on each one and pretend that it doesn't have any calories.