Line 2 baking trays with parchment paper. And put an extra piece of parchment aside for rolling.

Add the oats and rye flour to a large bowl. Bring water to a boil and pour over the oats & flour. Let sit for 1 hour.

Preheat the oven to 325F/162C. After 1 hour, add the next 7 ingredients, ending with the rosemary. Mix well.

Divide half of the mixture onto a piece of parchment paper and flatten a bit. Then place another sheet of parchment paper on top and using the rolling pin, roll as thin as possible. (It took up most of my cookie sheet.)

Repeat with the other half of the dough on a clean sheet of parchment paper, using the same piece you used before on top for rolling.

Place each sheet of dough-covered parchment onto a baking tray and sprinkle each sheet evenly with 1 tbsp of ground flax seeds and a little sea salt. (Sprinkle a little more rosemary if desired.)

Place into the preheated oven and bake for 10 minutes. Then remove and score/ cut the crackers with a knife or metal bench scraper into your desired size/ shape. Place back into the oven.

Bake for 20-30 minutes more, rotating the pans ( front to back and top to bottom) about half-way through. The baking time will vary depending on any add-ins/ substitutions you included. They should brown on the edges a bit and should not bend when slightly cooled, but be crispy and snap apart where you scored.

Let cool completely then store in an airtight container at room temperature. They will keep for about a week, but I doubt they will last even half that time. Enjoy.