Ham Croquettes - Failed

I have come to the conclusion I should give up deep frying. Truth be told I actually hardly ever deep fry anything at all. But have tried deep frying this past month a couple of times. These are supposed to be ham croquettes and they are, but they failed. I spent a lot of time and ingredients making them and they were slightly raw in the middle. I probably didn't leave them in the oil long enough. Whoa is me! They had an egg batter, two kinds of cheese, and uniformly cut up pieces of ham inside. They should have been delicious. Gusss I am so used to everything I make turning out, I can't hande when one thing doesn't. I was so frustrated I forgot to take a photo of them on the bed of the sauce I made.
 

We each got two ham croquettes in this serving dish. You'll just have to imagine the nicely presented dish. The shallot and tomato bed was quite delicious. Neither one of us could detect any ham flavor coming from the croquette, perhaps because they weren't cooked through.

Perhaps it's the same faulty temperature gauge I had for the fried frog legs. This is the replacement the company sent me, but I still think it's cooking things at a much higher temperature than it reads. Then there is my glass top electric stove; it's hard to controll the temperature on the burners. I wish I had gotten gas when I replaced our stove a number of years ago. Can I justify getting an air fryer? I need to do more research on that since I rarely eat fried foods. But maybe there is a benefit to them. Do they use any oil or just bit? Can you tell me your experience for frying and with what type of set up? Back to the drawing board.