Does anyone else's cookies spread way too much?

I see this one a lot up here in Canada, and the recipe usually gets blamed first. Most of the time it is the oven, not the dough.

If your oven runs low, the butter liquefies before the flour and egg have a chance to set. The cookie slumps into a puddle because nothing has firmed up yet to hold its shape.

Check the real temperature with an oven thermometer before you change anything else. Dials can be off by enough to matter.

Then run one test tray at 375F with tall frozen scoops. The tall frozen scoops hold their shape while the oven does its work, and one tray tells you if the temperature was the whole problem before you bake the full batch.

Asked on r/Baking

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