Using a small bowl, beat the egg white until you feel that it is now foamy. Once the foam appears, slowly put in the sugar and start beating it until you see it becoming thick and glossy. That is when you set it aside.
In another larger bowl, whip the heavy cream that you have and then be very careful when putting in the almond essence, macaroon crumbs, chopped cherries (both red and green), as well as ground almonds. Mix them and then add the other mixture into this bowl.
Take out eight identical baking cups of medium size in which you bake muffins and spoon out the mixture from the bowl. Using the slivered almonds, sprinkle them on top. You will then cover these baking cups with plastic wrap first and then aluminum foil and then place it in the freezer overnight.
Before you serve the almond tortoni, make sure to let it sit outside at room temperature for approximately 5 minutes and then serve it after you garnish it with halves of cherries.