This is not my recipe...I copied it straight from something Rachel (Msjinkzd) posted on another forum in a thread about invert food recipes. It is the best one I have found yet though, and my snails love it!
1 can of baby food (4-6 oz)
1 tsp+ fish food (may be omitted)
Calcium/vitamin supplements (I use 1tsp Jurassi-reptical powder w/out phosphorus)
1 packet (= 1 tablespoon) unflavored gelatin
You can select any fish food and any flavor of baby food that you like. Try to find baby foods with at least 4% calcium (vegetable medley has a higher %), either fruit or vegetable types are find. This is a good way to feed fish foods that are good for snails but don't sink, like freeze-dried shrimp, or fish foods that have a strong smell when cooked in other recipes. You can mix in much more than a teaspoon of fish food, and including the ingredients of a "snail trail mix" instead of a single fish food would make this snail treat more nutritionally complete.
Open the baby food and pour it into a small bowl. Heat the baby food in the microwave for 60 seconds (caution, it will be very hot).
Stir in the unflavored gelatin (add it slowly to avoid unsightly clumps of gelatin; don't use a blender or you risk creating air bubbles that will make it float) crushing any lumps with the back of a spoon.
Add calcium supplements and vitamins if you have/want them. Stir thoroughly.
Pour this mixture into a dish with a flat bottom (tupperware-type containers work well; if you are doubling or tripling this recipe, you might consider a pie pan).* Fold in your fish food(s) if you are adding any.
Refrigerate for several hours, then return and cut into cubes.
One jar of baby food yields a good handful of snail treats. Keep them refrigerated until serving. These sink and hold up pretty well in the tank, but as with any food, large uneaten portions should be removed after the snails have finished. These can be frozen for up to a month.
*You can use an ice cube tray to create big treats for a tank full of snails. No slicing is needed in this case.