Preheat your oven to 350 degrees F and grease a 9 inch pie dish or casserole dish.
In a large bowl, whisk together your tapioca flour, almond flour, xanthan gum, baking powder, and salt.
In a separate bowl combine your melted butter, sweetener, eggs, apple cider vinegar, and vanilla extract.
Add your wet ingredients to your dry mixture and mix until combined, your dough will be sticky.
Add 2 tbs warm water to your dough and mix well. Let your dough rest for 5 minutes to firm up. While your dough rests melt together all of your filling ingredients in 30 second increments until smooth and set aside.
Now make your topping by whisking together all of your ingredients and spread evenly on the bottom of your greased dish.
On a piece of parchment paper, spread about 1 tbs of tapioca flour so it covers about 8X12 inches. Take your dough and place it on your working surface, cover with parchment paper and roll your dough with a rolling pin into a 8X12 even rectangle.
Spread your filling mixture evenly over your dough, leaving at least a 1/2 inch around the edges.
Using the short side (the 8 inch side) carefully roll your dough rectangle into a log. Cut into nine equal pieces. Place your rolls in your greased dish and bake for 25-30 minutes.
Allow your buns to cool for about 10 minutes and then carefully (with oven mitts on) flip your dish over onto either a baking sheet or parchment paper so your delicious sticky bottom can run over the buns. Serve immediately, warm.