Preheat the oven to 325F. Line a large baking sheet with parchment paper.
In a large bowl, whisk together the almond flour, coconut flour, baking powder and salt.
In a medium bowl, whisk the eggs until blended. Whisk in the oil, honey, lemon zest and vanilla
Add the egg mixture to the flour mixture, stirring until completely combined. Add the almonds, if using
Scoop the dough onto the prepared sheet and shape into an even, rectangular log that is about 3 inches wide, 12-13 inches long and ¾-inch high.
Bake in the preheated oven for 20 to 25 minutes until golden brown and set at the center. Place sheet pan on a cooling rack and let cool for at least 30 minutes.
Use parchment liner to lift log to a cutting boar. Cut crosswise into ¾-inch wide slices. Return parchment to baking sheet and arrange slices, cut side up, on sheet pan. Return to oven and bake 10 minutes; turn over and bake 5 to 10 minutes longer until cut sides are golden. Turn off oven and cool completely in oven.