Crust:

1. Line a 9 " square baking pan with aluminum foil.  Make sure the foil hangs over the edges a bit (see photo).  
2. Preheat oven to 350°.
3. Melt the butter in a medium bowl and mix in the brown sugar substitute, vanilla and salt.  Stir in the almond flour and mix until blended.  
4. Press the dough onto the bottom of the lined pan and smooth it all over.  Bake for 12-15 minutes, until light golden brown.
5. Remove from pan and sprinkle the chocolate pieces over crust.  Let it sit for a few minutes to melt into the crust. Then use a spatula or pastry brush, gently spread the melted chocolate over the crust. (see photo).  Let cool and refrigerate until set and chocolate is hardened.

Filling

1. In a medium saucepan, combine the sugar substitute, cocoa and salt.  Stir in 3 tablespoons cream and whisk together to form a smooth paste. Whisk in the remaining cream and almond milk and stir constantly over medium heat.  Make sure to stir the bottom and sides of saucepan to avoid pudding sticking and getting clumpy. Using a rubber spatula or wooden spoon makes this easier.
2. Keep stirring until pudding begins to come to a low boil, which will take 4-5 minutes.
3. Lower heat to just a simmer and add in the chocolate.  Keep stirring bottom and stir along the sides as well to cook the pudding for another minute or two after chocolate has melted.  Then slowly sprinkle in the arrowroot and xanthan gum, stirring well to avoid clumps. * Continue stirring as you see the pudding thicken for another minute.
4. Remove pan from heat and scrape the pudding onto the crust.  Quickly smooth the top just once or twice with spatula and no more as it will begin to set up.  You can give the pan a slight jiggle if the pudding seems uneven in the pan and then leave it untouched for an hour as it cools to room temperature.
5. Place pan in refrigerator uncovered until completely cooled.  Then cover and remain in refrigerator for 2 hours or overnight.
6. To remove pudding bars:  hold edges of foil and lift from pan onto a cutting board.  Using a long handled knife or spatula, slide the bars off the foil.  
7. Heat a knife under hot water, wipe off and cut pudding into 16 bars.  You can reheat the knife and wipe off if pudding is sticking to the knife and you want a cleaner cut.
8. Store any leftovers in the refrigerator covered with plastic wrap or in a closed container.
9. You can sprinkle some chocolate shavings over top for decoration, optional.