Heat oven to 300°. Cut a piece of parchment the size of a cookie sheet and spray with avocado or olive oil. Melt the butter and set aside.
In a medium bowl sift in almond flour, baking powder, garlic powder, 1/4 tsp coarse ground sea salt and mix well. Using the small size cheese grater, or a zester, finely grate the cheddar cheese. Mix well into the flour, then knead in the egg white and melted butter until fully combined.
Dump onto the oiled parchment paper. Spray a sheet of wax paper with the oil and place over top of the dough. Roll out into a rectangle as best you can, until the dough is about 3-4mm in thickness. Patch where necessary. The rectangle should be about 20cms by 30cms.
Remove and discard the wax paper. Cut the dough into squares using a fondant cutter, knife or pizza wheel. Do not separate the crackers. Sprinkle a pinch or two of coarse ground sea salt evenly over the surface of the crackers. Slide the parchment onto a baking sheet and bake on the middle rack, in the preheated oven, for 10 minutes.
Remove the baking sheet from the oven, then slice the crackers along the cut edges. Separate the crackers, flip them over and space them out evenly throughout the baking sheet. Bake for 5-10 minutes longer, depending on how thick the crackers are, until lightly golden brown. You may need to remove some, then bake the rest for longer until each is lightly golden brown.
Cool completely and enjoy! Store in an air tight container at room temperature. These beauties will be in their prime for up to 7 days.