This is more of a store cupboard soup for when sweetcorn is out of season and I fancy something quick and easy to make, but with a little luxury of crab. It works just as well though with fresh sweetcorn when it's available. 

The key to this is a good shellfish stock which makes all the difference. You can use shop bought stock if you so wish, but it is easy to make and I've included a recipe on how to prepare the stock.

In summer you can use fresh, instead of tinned corn. 
1 tin or jar of sweetcorn 
1 tin of crab meat or cooked claw meat shell removed
2 cloves garlic finely chopped
1 onion finely chopped
700ml shellfish stock
Small 20g tub of creme fraiche
oil for frying
Salt and pepper to season

Cook the garlic and onions for 3 minutes on a medium heat until soft
Add the stock, crab and sweetcorn and cook for a further 10 minutes 
Blitz the soup in a blender until smooth and then put back on the heat, stirring through the creme fraiche 
Season with salt and pepper

Fish stock
Tip: I save the shells from whenever I eat shellfish and store them in the freezer until I have enough to make the stock. 
I have also been known to ask the chef to let me keep the shells, if I happen to eat shellfish when in a restaurant (yes, really!). 
Do not use mussel or oyster shells.

Shells and heads from lobster/langoustines/prawns/crayfish/crab 
100g shell on prawns
1 carrot roughly chopped
1 onion roughly chopped
2 cloves garlic
1 stick celery roughly chopped
1 bay leaf
Sprigs of parsley
5 litres of water

Place all ingredients in a large stock pan and bring to the boil
Lower the heat and simmer for 2 hours
Remove any scum that rises to the top as it cooks
Strain the stock and reduce by half
Allow to cool and keep in an airtight container until needed
It will keep in the fridge for up to a week and in the freezer for several months.