Preheat the oven to 350°F (180°C).
Heat the butter in a large skillet, add the lobster, saute thoroughly.
Blend in the mornay sauce and half the cheddar, reduce heat and simmer for 3 minutes.
Spoon the mixture evenly into the crepes.
Roll and place crepes in a greased casserole dish.
Sprinkle with the remaining cheese.
Bake in the oven for 15 minutes, serve at once.