The meltdowns have begun. They are soooooooo dramatic

I think he should be an actor!
Scenario. We are in the car and he pulls my nose spray bottle out of my bag as i'm lifting him out of the car seat (I know I know but it's always something he finds that is inappropriate to hold and play with). I take it back and he FREAKS. I am carrying him to the store and he's kicking or does the whole forearm to Mommy's throat thing. I try to put him in the shopping cart, no can do. He's strong and wiggling and just no way. It's embarrassingly loud, he's really hysterical now. I decide to carry him and take the items up to the counter one at a time (fun, he feels like he weight a thousand pounds at this point, A WIGGLING THOUSAND POUND MONSTER! But hey, all in a days work.
I put him down for a second mid tantrum just to pick up something I dropped and he throws himself on the floor like a cartoon character having a tantrum and is literally kicking and screaming!
Now the whole time I know the solution is a cookie but he's going to turn into a spoiled obese brat if i keep shoving cookies in his mouth....still, we are in public so i grab a box of cookies, tear it open and pop one in his mouth and he's fine. Like someone turned the off switch.
The thing is he's doing this 2 or 3 times a day. I can't keep putting cookies in his mouth! I also don't want to totally ignore him.
I read somewhere to say to him something like "Hey E I know you've got to do this thing and it's ok so if you need to cry go ahead and cry" and then leave the room for a minute or so. It said if you come back usually the storm has lost a little steam.
But what about when that doesn't work? What about in public? THe cookie thing is just so NOT the kind of thing I believe in. Works great though!
I keep thinking if i keep with the cookies he's going to turn into the fat kid in Willy Wonka, or worse, the spoiled kid!