Frosted Jam Cake Icing

Combine the cream and sugar in a heavy saucepan and bring to a boil,
cooking at a full rolling bois for 2 minutes, (A candy thermometer will
read 234 degrees F.) Cool slightly, then beat until it just begins to
thicken. Beat in the butter and immediately spread between the layers and
on top of the cake leaving the sides unfrosted. Decorate with the pecan
halves.