A pound of uncooked white rice is $0.69, and it has 1696 calories, which works out to 24.6 calories per penny. That's about 19x better by your metric.
Throw some veggies in with the rice and some soy or teriyaki sauce, and you've got a healthy meal that is compatible with most diets. If you're a meat eater, you can cook some chicken breast to go with it; if not, some tofu for protein will help make it more filling.
I acknowledge that a person's time isn't always tradable for wages, and that home cooking is generally cheaper and more satisfying.
Time-wise fast food isn't as efficient as it would seem at first glance. If you go during a normal meal time (which you pretty much have to do if you have kids), between travel time and waiting at the register, it's going to end up taking as long as a home cooked meal.