Toast the almonds in a dry pan over low heat for 3-5 minutes. Cool and chop. Crush biscuits into crumbs, mix in chopped nuts and melted butter. Fill glasses with the biscuit base and put in the fridge to chill.
Zest grapefruit and lemons, cut them in half and juice into a measuring cup. Split your vanilla bean in half with a sharp knife and scrape the seeds out, add the seeds and the bean to the zest.
In a small pot combine sugar, citrus juice, zest, vanilla bean and seeds, bring to a boil over medium heat, turn the heat down and let it simmer for 15 minutes until it turns into a syrup. It should coat your spoon when it's done but shouldn't be too thick.
Take it off the heat, add cream and put it back on the stove, heat it gently over low heat while stirring for 10 minutes. Cream will thicken.
Take it off the heat and strain the cream filling through a fine sieve to catch zest, vanilla bean and all other bits. This step will leave you with a silky smooth pudding.
Take your cups and glasses out of the fridge and fill them with the cream mixture. Put them in the fridge to set for 2 hours. Serve garnished with orange, lime and lemon zest or white chocolate curls!