Decarbing makes huge difference in quality...
I grew up working in a bakery from age 10 until well after high school. An older hippy baker caught me trying to make brownies when I was about 16 and went about teaching me instead of busting me.
I still do it the same today as I was taught, not to say I haven't tried other ways but best results are what I learned then.
Put a sheet of baking parchment on a lipped cookie sheet (nothing sticks to sheet and nothing is lost plus it doesn't make the kids chicken nuggets taste like weed the next day)
Preheat oven to 225F - Use a internal thermometer don't trust dial
Decarb for 1 hour
then onto whatever oil
I have used butter, olive oil and coconut oil as well as others. If you use butter clarify it first.
I tried to research what oil could hold the most THC for say a specific amount of each oil and all I could come up with that coconut oil had highest fat content. My thinking was if a recipe called for 1/4 cup of oil or butter how much stone could I get into that 1/4 cup?
I looked at different oils, crisco, and even peanut butter - hard to find data to compare.
At some point I figured adding more weed would be a waste, a diminishing return.
With the highest fat being in coconut oil it is what I tend to use as it has its own health goodness and being it behaves like butter where it can be melted and return to a solid it lends itself very well to any recipe calling for butter. I might be wrong but I think it has longer shelf life as well.
I typically use 1oz of sugar leaf for every 1/4lb of butter/oil so 4oz of weed to a whole package of butter.
In a pot with weed and oil/butter I add few cups of water to regulate possibility of burning.
Water helps later with leeching out the chlorophyll taste.
I boil for 10 minutes then go to low heat for 8 hours.
If water level drops too much I add more so oil or plant matter doesn't burn.
I tried 2,4,6,24,36 hours but 8 made it right.
I strain with cheese cloth into flexible plastic bowls with slanted sides and lids. Makes it easy later to twist bowl and get solidified cannabutter out with out breaking it.
I rinse the bottom of it to get any residual water/green matter off and pop back in freezer until I use.
I get great goodies, for some they are too powerful so options are to eat less, or cut your recipe with non-cannabutter/oil.
I live in a legal rec state and have bought treats from stores with basically no results, last test I hate entire $30 bag of brownie bites and felt nothing.
Something else I found makes it all taste better in the end is cure the sugar leaf in jars for weeks/months just like you do flowers = makes for less hay chlorophyll taste that the water leeches out. I can make a cookie that tastes like a cookie with no weed in it.