Melt the lobster butter in a saucepan.
Add the flour and cook, stirring for a few minutes.
Regarding the stock, I had used some canned frozen lobster for the lobster ravioli recipe, so I squeezed out the juice/broth from there and reserved it. That gave me about 1 cup of stock, and I added another cup of chicken stock. You can use all chicken stock, but it won't be quite as pink, or have the same lobster flavor. If you should be fortunate to have lobster stock, feel freeze to use it. Add the stock to the butter and flour.
Stir in the cream and adjust seasonings with salt and pepper. You could spice it up with a little cayenne if you want.