At least seven hours before baking, prepare the dough for a long fermentation. Start by cutting the butter into the flour until it is in small pieces. Stir in the starter, sweetener, and milk until a soft dough just comes together. Cover and place in a warm spot in your kitchen for 7 to 12 hours.
Preheat oven to 350°F. When ready to commence baking, combine salt, baking powder, and baking soda in a very small bowl until evenly mixed. Sprinkle this over your fermented dough and knead until it comes together into a cohesive, soft dough.
In a small bowl combine filling ingredients until they form a paste.
Roll dough out into a ¼ to ½ inch thick rectangle. Spread filling evenly over dough. Roll dough tightly and cut into ½ inch thick pieces.
Place in a 12-inch cast-iron skillet and bake in pre-heated oven for 20 to 30 minutes or until golden brown on top and bottom.
