The hardest thing about writing a cookbook is writing down the recipes by the time I'm a shake, rattle and stir cook. I seldom measure. My eye knows a quarter cup, liquid or solid, when I see it. (I can't do metric though.) So the only reason I could give you a recipe yesterday was that I had just made my wraps for the picnic. even so I guessed at the amounts I was using, except for the imitation crabmeat that comes in a package and I can read the amount, and the eggs that I can count. They were large, free-run. So now you know my secret.
I have published three cookbooks and I did all my own cooking and testing. Well, I got friends and family to help with the testing, that is, eating. They didn't mind. I dedicated my first cookbook to my children who ate my failures. But I got so I would compose a dish at the typewriter (in those days it was a typewriter), and then go to the kitchen and try it out.
Nowadays professional cooks have test kitchens and helpers. It's expensive, all that food. For my second cookbook (about cheese), it was costing me so much I asked my publisher (I was under contract) for some financial help. They gave me $2000 for food expenses but my agent insisted on her 10%. I protested that it wasn't an advance or pay, it was just to help me pay for the food, but she insisted. I never forgave her for that.
Well, life isn't always fair. The good thing is, I still use my own cookbooks.