In a small bowl, beat egg white until foamy. Gradually beat in sugar, and continue beating until thick and glossy; set aside.

Whip cream in a large bowl. Carefully fold in sherry, almond extract, macaroon crumbs, ground almonds, and chopped red and green cherries. Gently fold egg white into cream mixture.

Spoon into 8 paper baking cups placed in medium size muffin tray. Sprinkle with slivered almonds. Cover muffin tray with clear plastic wrap, then wrap with aluminum foil. Freeze overnight.

To serve: Let sit for 5 minutes at room temperature, then garnish with maraschino cherry halves.