Put 2/3 cup oatmeal in a food processor and grind until fine in texture, similar to flour. Add to medium sized mixing bowl.
In the same food processor, puree cranberries. If you are using fresh or defrosted berries, it will likely be a liquid. If they are frozen, it will typically look like a coarse meal (see pictures). Add cranberries to the bowl.
Add the flour, 1/4 oats, ground flax seed (optional), honey, and yogurt to the bowl. Mix the ingredients together until incorporated and the dough holds together. The water content in the berries can affect the moisture in the dough. If it is too wet, add a little flour at a time. If it is too stiff or not combining, add a little water at a time.
Lightly flour a large cutting board or clean counter. Flip dough out onto surface and roll to 1/4 inch thickness.
Cut out cookies in the size and shape you want and place on a sil pad or parchment lined baking sheet. The cookies can go close together as they will not grow much in size.
For soft cookies: Bake for 15-18 minutes. Remove from oven and cool on rack. Store in refrigerator for up to two weeks.
For hard cookies: Bake for 15 minutes then flip cookies. Bake an additional 15 minutes. Turn off the oven and leave the cookies in the hot oven for approximately two hours. Cookies will be hard and crunchy. Let cool completely before storing or else the heat will cause them to turn soft again. Store in air tight container for up to one month.
If making smaller cookies, the cooking time will greatly decrease. Cook until the edges begin to brown.Make these gluten free by omitting the flour, blending 2 cups of oats into a coarse flour in a food processor, and mixing in a cup of whole oats. Adjust as needed for moisture.