melt butter in a stockpot over medium heat. add the onion and bay leaf, sweat down for 2 minutes until translucent. sprinkle in the flour and stir until it dissolves. whisk in the stock, stirring constantly until smooth and free of lumps. gradually pour in the milk, cream, and paprika; continue to stir until incorporated. add half the crab meat and roe. season with salt and pepper. cook for 15 minutes until thick and heated through. to serve, divide a tablespoon of sherry among 4 bowls. ladle the soup into the bowls, spooning the remaining crab meat and roe in the center of each. garnish with chopped chives. serve with crusty french bread.