Line 1 - 9 x 13 inch pan and 1 - 8 x 8 inch pan with plastic wrap. Spread ice cream into a 1 inch layer in the pans, cover with plastic wrap and place the pans in the freezer to refreeze.
Beat the butter with an electric mixer for 1 min and then add the brown sugar. Continue to beat until light and fluffy, 2-3 mins. Add the egg and beat until well blended.