Make the Caramel Toffee Sauce first (see link in Recipe Notes to Caramel Sauce recipe) -OR- make the Caramel Sauce while the cake is cooking in the Instant Pot.
Grease small bowl or leak-proof cheesecake pan suitable for fitting inside your Instant Pot insert (see the one I have and the link in Recipe Notes below). Set aside.
Pour 2 cups water into Instant Pot insert. Place trivet into bottom of pot.
Place pitted dates in heat-proof measuring cup (ideally with a 2 cup minimum measurement capacity). Add boiling water, ONLY to the 2 cup line (you won't quite use all the water) and allow to soften 1 hour. (If you don't have a 2-cup or larger measuring cup, you'll have to place dates [not packed] in 1 cup measuring cup more than once, then add water to fill line to measure.)
While dates soften, combine dry ingredients in medium size bowl: cassava flour, coconut sugar, baking soda and sea salt.
In small bowl combine wet ingredients: melted butter, milk, egg and apple cider vinegar. Whisk briefly.
Place dates and water in blender and puree 15 seconds.
Pour date puree into dry ingredients bowl. Add wet ingredients. Stir and fold together well without over-mixing. Scrape contents into prepared pan and briefly smooth the top surface. Cover the pan with tin foil over parchment paper and place pan in IP insert on top of trivet; or use parchment paper and place a small salad plate over the paper (to keep it down and somewhat dry during cooking).
Seal Instant Pot lid. Make sure steam valve is shut. Press "Manual" button and set the time to 30 minutes. When timer goes off, allow the pressure to release naturally for 25 minutes. Then press "Cancel" button and open steam valve. Open lid and remove baking pan by using trivet handles and hot pads.
Tilting the pan to one side slightly to allow any water to roll off, carefully remove tin foil (or plate and parchment). Allow cake to cool to room temperature. If using cheesecake pan, remove pan's sides.
Remove cake from pan, and place on plate. Using about half the caramel, pour warm caramel sauce all over cake's surface. Top with optional whipped cream (or coconut whipped cream). Garnish with pomegranate seeds, red currants or cranberries, fresh rosemary and any other desired seasonal produce. If using whipped cream (highly recommended!), drizzle with additional caramel.