Mix the eggnog, milk and the pudding until thickened.
Whip the heavy cream to a MEDIUM consistency and fold into the eggnog and pudding mixture.
Add the extract and mix well. Spoon into individual dessert dishes.
If desired, it can be decorated for the holidays with red and green maraschino cherries. Cut the red cherries in half (to resemble holly berries) and cut the green cherries into quarters and arrange them around red cherries to resemble leaves.
Store mousse in the refrigerator, covered with plastic wrap, until ready to serve.