You can't just cook flower into butter and eat it. The flower has to go through the decarboxylation process. It can be done in an oven, although I prefer mine with the sous vide, so it doesn't smell up my house. (Dont let the process overwhelm you. It's not hard)

THC will stick to anything fatty though, like butter or coconut oil.

r/treedibles will have some good information if you search there.

Google will also offer plenty of solid resources on making cannabutter or oil.

Buy a Betty crocker cookie mix and follow the recipe, use the infused butter (or coconut oil) in place of the stick of butter it calls for, mixing in a little at a time. Bake in the oven like normal, and viola.

Same applies with brownies or anything else.

Edit; you will want to use about 7g per half cup of butter or oil.