If you've got powdered hash, you can just toss it in your brownie mix or whatever else you are using. So long as the hash gets baked or heated with some sort of fat source (olive oil in the case of most of the instant bake mixes) it will decarboxalate and become more orally active. I used to mix it in w/ instant muffin mixes and make Raspberry hash muffins, and sometimes I will knead it into pizza dough for hash pizza. The amount to use is pretty subjective, everyone has a different answer on how much the like to use. I've found that a "dose" of hash in edibles is anywhere from 0.05-0.3 grams depending on the quality of the hash and the tolerance of the person. Watch out though - hash food can kick your ass if you are not careful. One time my old room mate and I powdered up a bunch of it and used it about 50/50 for a flower substitute in a cookie mix. Each cookie ended up having 2+ grams of hash in it, and they were total overkill - everyone who ate one either passed out or hallucinated.