Remove the lobsters from the water and place on a large sheet pan. When cool enough to handle, remove the claw and tail meat and save any roe you find. Chop the meat coarsely and refrigerate.

To make the sauce, sauté the shells with the vegetables in the butter in a heavy Dutch oven. After the vegetables have wilted, add the peppercorns, thyme, any lobster juice and tomato paste. Add water to almost cover, cover the pan, and simmer for thirty minutes. Remove the lid and strain into another pot.

Reduce quickly until the mixture thickens slightly, and is a little more intensely flavored than you want. (Since the resulting liquid is often salty, don't add any salt.) Add the cognac and cream and remove from the heat. This sauce/soup can sometimes vary in intensity, so add the cream a bit at a time until you like the result. Swirl in the remaining tablespoon of butter, and add ground pepper to taste. If the liquid tastes good but is thin, you can use a beurre manie to thicken (equal parts softened butter and flour combined, added to the hot liquid and quickly whisked in). Start with one tablespoon of each and go from there.

For the crêpes, put the ingredients into a blender and whirl until combined. You may need to use a rubber spatula to scrape down the sides if the flour sticks. Let sit in the blender in a cool place for at least ½ hour. When ready to cook, heat a large crêpe pan or slope-sided saucepan until hot. Whirl the mixture again until bubbles appear on the surface. Add a thin film of the oil or clarified butter to pan and ladle in approximately 1/4 cup of the batter, moving the pan to coat the bottom. Cook for a few minutes on the first side and then turn for about 30 seconds. Remove and continue to make more crêpes until the batter is used up. Unless you are very practiced it may take a few tries to regulate the heat to the ideal point (the same principle as when the first pancake never comes out right). You only need four crêpes for two servings, so you can freeze any which are left over.

Prepare the filling by sautéing the mushrooms and the shallot in the butter over high heat. When almost cooked, add the lobster meat for a minute or two. Add salt and pepper to taste, and remove from the heat.

To serve, put 1/4 of the filling mix into each crepe and roll. Put the rolls into a buttered pan (such as a square cake pan), and pop into a 400° oven for five minutes. Plate the crêpes (heated plates would be a nice touch), and top with some of the sauce and reserved lobster roe (if available).