I have been making the same chocolate-chip cookies for a while. Last week, after baking a batch and removing from the oven, they expanded and became flat.
Usually they stay in the same shape when removed from the oven, (thick and chewy) this time is the only time my cookies really expanded and became flat.
I bake them from the freezer.
What could have gone wrong? too much or too little baking soda? I usually put 1 tsp of baking soda per 3 1/2 cups of regular white flour.
There are many reasons why this can be happening, cookies will spread more if the oven is not at the right temperature, try preheating for 20 minutes before you put cookies in the oven. Our ovens sometimes change through time and it might not be hot enough. Another thing could be that you added more sugar than before, sugar tends to make the cookies also spread if you add more that you were supposed too. Another one could be, since air will cause cookies to spread, you don't want to whip too much air into the cookie dough when you're creaming the butter and sugar together. Only cream for as long as it takes to combine the butter and sugar, which might only be 30 seconds or so. Beyond that and you're just incorporating too much air. SO check on this things and maybe something here rings a bell, this has happened to me when I have substituted margarine for butter, and sometimes yeah I tend to cream a bit long cause I get distracted. So yup check on this things :)
There are number of reasons behind this like may be you used baking soda in your recipe.Now a days baking powder is used by bakers to make the perfect cookies. Softened butter is used instead of melted butter and make sure to cool down your cookie dough before baking.
Some other thoughts:
