Preheat your oven to 325F.
In a mixing bowl, combine the almond flour, ground flaxseed, finely chopped walnuts, sesame seeds, minced fresh rosemary, 1/2 teaspoon of the flaky sea salt, and black pepper. Stir until evenly mixed.
Add the egg white and olive oil to the dry ingredients. Mix until a cohesive dough forms that holds together when pressed.
Place the dough on a sheet of parchment paper. Lay a second sheet on top and roll the dough out to about 1/16 to 1/8 inch thickness. Remove the top parchment and sprinkle the remaining 1/4 teaspoon of flaky sea salt over the surface.
Score the dough into 1.5-inch squares or rectangles with a pastry wheel. Transfer the parchment onto a baking sheet.
Bake for 18 to 22 minutes until golden brown and dry to the touch. The crackers in the center may need an extra minute or two.
Cool completely on the pan, then snap apart along the scored lines. Store in an airtight container for up to 10 days.
