Heat 1 cup of heavy cream with chocolate chips over medium-low heat, stirring constantly, until chips have melted. Set aside.
In a medium bowl, beat eggs and sugar with a hand-held mixer at medium speed for 3-minutes.
While mixing on the same setting as above, slowly add the melted chocolate mixture to the egg mixture. Stir in the orange zest, if using. Once combined, pour back into the pan used to melt the chocolate. Heat over medium heat, stirring constantly, until thickened.
Remove from heat and cool slightly before transferring to the refrigerator to chill for 2 hours.
Once chilled, whip the remaining heavy cream until stiff peaks form. Gently fold the chilled chocolate into the whipped cream until thoroughly combined. The mixture should have a fluffy consistency. .
To serve, spoon chocolate mousse into a piping bag and pipe into small dessert dishes. Top with whipped cream and maraschino cherries or mandarin oranges, if desired. Enjoy!
*Tip: The orange zest adds a really nice pop of flavor to this recipe.Optional, to serve:Whipped cream, maraschino cherries, and/or mandarin orange slices