Combine all the dry ingredient for the cookie dough in a large bowl.
Blend in the butter, using your hands to crumble it evenly into the dry mix.
Stir in the remaining wet ingredients until a dough begins to form. The dough may seem a little soft and dry at first but let it sit for about 5 minutes to firm up.
Place the dough on a piece of parchment paper and roughly shape it into a rectangle. Place another piece of parchment paper on top of the dough and refrigerate for at least 20 minutes.
Remove the dough from the fridge and, keeping it between the parchment, roll it into a rectangle about ½ inch thick. If the dough cracks a little, just press it back together.
Brush the dough with the melted butter for the filling then sprinkle with the cinnamon and erythritol evenly across the entire dough.
Roll the dough from the short ends of the rectangle all the way up so it is in a tight log.
Slice the log into ¼ inch thick pieces and place on a lined sheet tray. Place the tray in the fridge for 20 minutes to chill.
Preheat your oven to 350 degrees F.
Bake the cookies in the hot oven for 7 minutes.
Whip all the ingredients for the frosting together in a bowl and then spread or drizzle using a piping bag over the cookies.