Sounds like the witch spell might be easier than teaching Agnes gardening and fishing, in addition to cooking. But, does she have to be a witch to do that?
A witch at level 8/9 can do a "sunlight charm" and at level 10 you can do the "reanimation ritual" it's much easier than the "Oh My Ghost!" Opportunity and faster than ambrosia if done right.
An easy way to level up a witch is (assuming you have the money) run to the spa for the most expensive package (the one that lasts for 7 days). Then, just cast the most updated spell you have over and over until you can magically update things. It's usually then that I line up several things that have multiple updates (stereos and the cheap dishwashers work really well) and I just line up with one upgrade and send her right back down the line for another upgrade. This works really well when paired with Alchemy and Steel Bladder LTR.
I had a resurrected Tragic Clown (by Agnes) in under a week without having to wait on the opportunity to hit. Make sure when you sunlight charm the zombie you resurrect that you cast a love spell on them (if you're aiming for Agnes to love him again) so you can become instant friends. Otherwise they'll walk off your lot and leave which is the only downside to witch magic. Then you have to call them back with your phone and try to schmooze them up to friends to ask them to move in.
