Copyright protection attaches to original, creative works of authorship. If a recipe is copyrighted, the copyright holder can usually sue anyone who copies it without permission.
Recipes typically have 2 sections: 1. the list of ingredients, and 2. the mixing & prep instructions.
1. Plain lists of ingredients are not copyrightable, or the protection, if any, is extremely thin. Protectability increases with the level of creativity or originality. If you write, “1/2 tsp salt,” you’re probably not writing a copyrightable list. If, on the other hand, you write, “an almond-sized dusting of lovingly ground sea salt,” you’re probably getting closer to something that you can protect.
2. Generic descriptions of how to mix ingredients are afforded very thin protection, again, unless they are more creative than usual. Flowery language, unexpected word choice, nonstandard presentation, and such may militate toward a finding of copyrightability. “Wisk the egg whites until they are as stiff as wet angels’ wings” — that sort of thing…
So, if you want a greater chance at protecting your recipes from copyists, make them more creative and original. Use unexpected, atypical language. Have fun.
If you want to copy someone else’s recipe, first ensure that the recipe is of the more generic, less creative kind. And if you do copy it, change the language as much as possible to something more interesting to make it your own. If you copy a truly generic, boring old recipe bearing no smidgen of creative content word for word, I cannot promise that you will not be sued by the copyright holder, of course, but you may have a reasonably strong defense that the generic, boring old recipe is not copyrightable.
You cannot, however, get away with copying a whole cook book or even a significant number of recipes from a single book, no matter how boring the individual recipes might be. The book itself will almost always be copyrightable, and copying too many recipes from a single book could constitute an infringement.