Cookies are surprisingly sensitive to slightly different ingredients or practices. e.g. Using different brands of butter, different sizes of eggs, or storing the dough at different temperatures can have a large impact on the final product, even though the same recipe was followed.

Baking in general is very sensitive. I've made batches of cookies that I've tried to reproduce for years but, because I didn't take notes, could not. Hell even the altitude you bake at requires significant adjustment.

Cooking is art. Baking is science.

The baking is a science meme needs to die.

When your baking you need to learn to react to the dough that's in front of you.

As someone who was a professional baker for years, agree. Baking very much has intuition and art like qualities. It's just less forgiving of loose measurements until you know what you are doing.

It's less for giving but not as unforgiving as some people make it out to be. Even less so when you don't demand commercial level consistent results that can be sold fungible products.

Though people have been baking in poor conditions for a long time. If peasants could bake bread without even a cast iron dutch oven maybe you can. Sure each batch is different but it works.

Volume-based measurements, too. One person's "half a cup" is not another's.

I've been much happier since I started weighing everything.

Getting a new oven has invalidated every single time written down in a recipe here. (usually not too hard to adjust, but still)

That's why you measure result wherever possibly - poke the cake with a toothpick and see how much sticks to it, measure internal temperature for large meats, bake until the outside reaches the desired appearance, etc.

I can speak to this - the main variations are in the kind of butter you use. Using salted, unsalted, or margarine result in similar yet different cookies. I personally use unsalted and feel like it creates the most “cookie” like experience. Flour brand and texture also makes a difference. You will get a very different result based on using the store brand vs (for example) King Arthur flour.

The tollhouse recipe is amazingly fragile. Slight variations in temperature can make the cookies "go flat" or end up with a thick skin. No surprise there is a variation of outcomes using older ovens that were very imprecise.

I mean, also, when was the last time you had your oven properly calibrated? How sure are you that it's actually 350 F?

IIRC this would mostly be temperature offset + ease of oven temperature swings in response to introduction of thermal mass; plus humidity and altitude (= air pressure.)

(If you want to learn about reproducibility, look up what the factories making the packaged-snack version of your food tend to control for!)

Two main mistakes that people make: 1. "scoop and dump" approach to flour. Flour should be spooned into the measuring cup so its not packed in. 2. over-baking cookies due to cooking too long or oven that is too hot or not hot enough.

The flour should not be packed? I've always done it like that, it seemed so obvious that that would give a less random result that having it loose. I guess I'll weigh it and check against the markings on my measuring cup next time.

Some pack, some sift and scoop. You have to know what the recipe wants. Weigh is in my opinion superior, it just wasn’t widely accessible before cheap digital scales.

In my four decades of baking, I have never seen a recipe that calls for packing flour. It is always sifted, spooned and leveled, or weighed.

Weighing is the only weigh.

Brown sugar should be packed; flour must not be — you’ll get substantially more mass per volume than the recipes assume.

four is alway sifted - to get the mouse droppings out. In our modern world nobody has mouse droppings in flour but tradition is still strong. Weighing doesn't care but if you are scouping as much air as possible is what the recipe assumes.

Or measure flour by weight instead of volume.

Flour should be weighed.

Well I mean weight vs volume, actual oven temp, full fat vs skim, salted or unsalted. There's a lot of little variables even "following" a recipe.

Even if you use exactly the same ingredients, there is the temperature of the butter and how good a job you do of creaming it. Then there are factors like how do you mix the ingredients, and for how long. These all affect the final product. Then there is the oven, and if the temperature is accurate, if it does a good job holding temperature, etc. That's a lot of variables for something as simple as a tollhouse cookie!

Why are you using chocolate chips? Real bakers get the cacao pods from the grocery store, ferment the nibs inside for a month, then carefully formulate their own chocolate to pour into boutique chips of their own making.

As other comments point out, there is no added value in the pre-made ones, make your own chips! Oh, and the mixing bowl, why not take up glass-blowing? It's relatively easy to make your own bowls.

My brother set out to copy out mother's pie dough recipe, so had her do it in front of him. He recorded every measurement, each step of the creation process, but it didn't work. The result was a perfectly serviceable pie crust, but noticeably inferior to our mom's. Maybe the humidity in the kitchen, or subtle changes in rolling style... mom could do it every time and we couldn't copy it.

The truth is, we were trying to short cut past the effort involved of mastery by making hundreds of pies over decades...