I worked at Carl's Ice Cream for 5 years in the late 80's and early nineties as a cashier. The place was always packed - I never got a break!
Since I didn't make the ice cream I can't tell you the exact recipes, but they ground up real strawberries, used Hershey's chocolate, and used real vanilla (washed with grain alcohol if I remember correctly) for the flavoring. Great stuff! They only have those three flavors...which was always funny because people would come up to the window asking for Rocky Road or Chocolate Mint and I'd have to point them to the menu...:-)
Simplicity is the theme. Three flavors of ice cream, the same flavors for the shakes (along with pineapple) and only a few sundae toppings as well (Hershey's syrup, hot fudge, pineapple, maplenut *yummy*, and real strawberry). However, they use the BEST hot fudge I've ever had in my life, Mellowcream Hot Fudge: http://profileshowcase.foodprofile.com/internetshowcase/GW/DFP000238/gateway.asp?MFR_NUM=000143&MFR_PRD_NUM=2700022000&GATEWAYID=DFP000238
I'd go out and buy this stuff for my own use. Once you have it on a hot fudge sundae you will NEVER want a different hot fudge. In fact, I recommend when you're there to ask for a "hot fudge shake" for a real treat. Or even better, a "hot fudge malt". Man, those were good. (These are not on the menu).
They used to have 4 slushie flavors, but now just root beer and cherry. I root beer slush float is a good choice here as well.
Here's a list of my favorite treats there:
1. Hot Fudge Malt
2. Giant Pineapple Maplenut Sundae
3. Giant Strawberry Nut Sundae Made with strawberry ice cream
4. Giant Hot Fudge Nut Sunday with Double-Fudge
5. Large Cone "Around" (meaning a large cone with all three flavors on it.
Also, I can't leave here without mentioning the Carl's "twist" that they put on the last scoop the goes on the cone. It gives each cone a little artistic flair that you won't find at other frozen custard stands.
Keep on eating!