Using a double-boiler or a heatproof bowl set over a saucepan of gently simmering water, add heavy cream and chocolate. Let heat, stirring occasionally, until chocolate has fully melted and mixture is smooth.
Add vanilla or {optional} liqueur; stir until smooth. (Note: If using liqueur, then omit the vanilla extract as it will be too much additional liquid.)
For Pineapple Christmas Tree
Slice off top of pineapple (i.e. leaves). (Note: You want to slice as close as possible to the leaves while still leaving enough of the pineapple for them to stay attached together.) Trim any excess pineapple off of the base.
Invert leaves and insert toothpick into top. The toothpick should stick about ~1” out of the top of the leaves. Stick maraschino cherry on the end of the toothpick. Sprinkle coconut flakes around the pineapple leaves.
Place “tree” on large serving platter and fill platter with fondue dippers (pineapple, bananas, marshmallows, pound cake bites, brownie bites, etc.)