I remember when we first did this (I forgot what occasion was it), my FIL said that we should do it often and I could understand why he likes it. At his age, he doesn't really feel like cooking for breakfast. Sometimes, he would forget that he is cooking and it get burned which he end up tossing in the garbage disposal so he would just eat snacks from here and there.
Anyway, we just cook the food that he normally enjoy, nothing very special.
After we ate breakfast, we hang out at his back porch and took some photos with him.
My own father died when he was 51 so when I came here in the US, I found a new father with my FIL. I always thank God that even though I am thousand miles from my family back home, my family here treated me like their own. To the most wonderful father-in-law in the world, who happened to be a World War 2 Veteran, happy birthday to you Dad. May God give you more years of good health so we can spend more time with you. We love you!