Add the egg yolks to a large bowl, with the granulated sugar. Whisk for 3 minutes, or until both get light in color.
In a large saucepan on medium-high, add milk and hibiscus. Heat until it boils, stir occasionally.
When milk begins to boil, remove from heat. Continuously whisk the egg yolk-sugar, while slowly pouring the hibiscus-milk in it.
After most of the milk is poured into the bowl, pour the entire mixture back into the saucepan, and whisk on medium-low for 5 minutes.
After 5 minutes, or when mixture thickens slightly, remove from heat.
Add the cinnamon, ginger, nutmeg and vanilla, and mix. Strain entire mixture into a bowl. Let sit for a least an hour, or when mixture reaches room temperature.
In a large mixing bowl, whip the heavy cream, until it reaches soft peaks.
Add a small amount of the soft whipped cream into the hibiscus bowl, and whisk. After, add the whole hibiscus-milk bowl to the large whipped cream bowl. Whisk everything together. It makes approx. 9 cups.
Refrigerate for a few hours or overnight before consuming for best results. Stir thoroughly and add alcohol of choice, before serving.