How to keep no-bake cookies from becoming grainy?
The common Peanut butter/oat/butter/sugar/cocoa recipe (there are variations on proportions, but not much). A friend growing up called them "chocolate death wads" my family always called them "Molly Cookies". The basic procedure is to boil sugar, cocoa, milk and butter, then add peanut butter and oats, spoon them out and let them cool.
When my grandmother would make these, they always had this lovely glossy sheen to them, and the mouth-feel was smooth (well, apart from the oats.) Every now and again I'll get that, but more often than not, they end up kind of crumbly and dry with a matte sheen, and the mouth-feel is grittier.
Most of the recipes I have seen talk about boiling for a certain amount of time, but I thought a temperature might be more precise for troubleshooting. When I used a thermometer and took it solidly into soft ball 235-240 range, they were even worse than usual. And sometimes, the early ones spooned out are fine, but it's the end of the batch, that cools off some before you get them dished that are the crumbly sort. Which seems to indicate that the cooking temperature isn't the culprit at all.
Has anyone else had this problem? Any advice?