Crush cookies; combine with melted butter in 9 x 13-inch pan; press onto bottom
of pan; freeze.
Soften ice cream and spoon over frozen crust, spreading evenly. Refreeze until
firm.
Topping: In top of double boiler, melt 6 tablespoons butter. Add scalded half
and half, chocolate and sugar. Stir until the chocolate melts and the mixture
thickens, about 20 minutes. Cool well; add vanilla. Spread over frozen ice cream
layer and refreeze.