After bringing 1 gallon or more of water to boil in a large saucepan, add a little salt. Drop live crawfish into the pot, and cook them from 3 to 5 minutes, depending on their size. Peel the crawfish tails. You'll need a full cup of cooked tail meat, which will require quite a few crawfish. It's best to catch a hundred or more, then eat what you don't need for the recipe. When peeling the crawfish, also be sure to get some of the "butter" out of the head section; to accomplish this, twist the tail back and forth a couple of times before pulling it loose from the head. The fat will be visible. Scoop out some of the head fat with a baby spoon, and mix it with the tails. Mince the tails, or mash them in a mortar and pestle; I use a chefs knife, first mincing and then mashing with the side of the blade. Melt 1/4 cup butter in a saucepan. Add the crawfish tails, cooking and stirring for about 10 minutes. Stir in the cream and cayenne, then remove from heat. Keep warm.