This recipe is originally from Erin Lives Whole. Her recipe calls for almond flour and coconut flour, making these gluten free! However; I've tweaked it a bit to be more to my taste (not a big coconut gal), so my version uses all purpose flour and is not gluten free. These get soft quick so I made a half batch that I did in a loaf pan and it made for 8 lemon bars, perfect for 2 people! If you want a full batch, double everything).