If you own a pressure cooker you will have a much easier time, or a crockpot with digital temperature control. Set oven/crockpot to 300-315'f, THC boils at 315'f so this is a great temperature to slowly melt the THCacid into oil. With the pressure cooker you are assured that even if the oven is hotter at the top, you won't loose any THC do to evaporation. Give it at least 2 hours for decent effect, over night is great, and 24 hours is going to get about as much out of the cannabis as you can. I know that some people suggest that you set a crockpot on low and cook it for 2 days, but that is just an asinine waste of time and human intellect. Then just combine the oil into the recipe, obviously strain out any particles, and make sure to cook your brownies at/under 315'f. Enjoy those tasty treats. I add in kief from my grinder into the batter before pouring, you won't get any texture change from it. Even if you don't have a pressure cooker you should get decent results by just roasting the oil in the oven with the cannabis. I prefer the oven to the stove top because of temperature control, and a pressure cooker is great because it keeps your house from reeking and you from wasting precious THC!
Good luck,
ILovePlants