Preheat oven to 350*
Line a 8”x11” baking pan with parchment paper leaving a bit of parchment paper hanging over the edge
In a mixer, beat butter and sugar until smooth and combined
Slowly add gluten-free flour, cinnamon and salt to butter and sugar and beat until combined and a dough begins to form
Once combined add dough into lined baking pan and press crust down into pan evenly
Place crust in oven and bake for 10 minutes
Add 1 C. of apple cider to a small sauce pan and reduce down to 1/2 C. and cool
Meanwhile beat eggs well for 2-3 minutes on medium
Add sugar, reduced apple cider, apple cider vinegar and combine another minute
Slowly add gluten-free flour and baking powder while continuing to mix
Combine on medium speed until well incorporated
Once done, remove crust from oven
Pour apple filling over crust and bake for 30 minutes
Once baked, cool apple bars for 1 hour
Using excess parchment paper, lift apple bars out of baking dish and place on cutting boards
Using a pizza cutter, cut apple bars into squares and serve