Baking – Could I substitute peanut butter in place of butter or crisco for cookies

Peanut butter cookies don't spread as they cook, so you have to flatten them before hand. This ensures that the middle will cook through before the outside burns.

As for the pattern created, it actually creates slightly more surface area, so you'll get more browning at the extra edges that you create. Think of it like a meringue, or the top of a shepherd's pie -- if it's too smooth, you won't get the little bits of browned crispy bits that you'd get if you rough up the surface.

Peanut butters that are not "all natural" include cheaper oils along with sugar and emulsifiers to keep the mixture from separating and to make it lighter and smoother.

That lack of emulsifiers could make a huge difference but it depends a lot on the recipe.

In a normal cookie dough fat is creamed with sugar and eggs are beaten in one at a time which adds a ton of emulsification power from the lecithin in the yolks.

Additionally- the fat will bind with the flour and be baked into the cookies. Like Jefromi- I have not had any problem with the fat from natural peanut butter separating out after baking.

If you made a cookie dough and either left out the yolks or didn't beat it well enough to properly emulsify- and then let the batter sit out for a while before baking I would fully expect the peanut oil to separate.