Make the coffee. You can use hot water and instant coffee, too.
Melt the butter and combine with the hot coffee. Let to cool enough you add the eggs without them to cook.
Add the eggs and mix well.
Combine all the dry ingredients and mix them with butter, <g class="gr_ gr_2882 gr-alert gr_gramm gr_run_anim Punctuation only-ins replaceWithoutSep" id="2882" data-gr-id="2882">coffee</g> and eggs.
Line an oven tray or pan with parchment paper and pour the mocha bar dough in it.
Bake for about 40 minutes.
Make powder sugar of the xylitol in a blender. Dust the xylitol powder on slightly cooled mocha bars and enjoy!
Tips
Regular mocha bars have over a double of sugar than what I used xylitol. Believe me, they are sweet enough with my recipe, too. I didn't do the traditional chocolate icing because of the amount of icing sugar, or in this case xylitol, the icing requires. First of all it's way too sweet for a sugar free life style and it might cause some serious stomach aches if you put that much of xylitol on your cake. :)