Is baking cookies a physical or chemical change?
When the materials are heated they undergo a chemical change. The reaction is non reversible. The sugar, flour and eggs can no longer be separated. The properties of the materials have changed so it is a chemical change.
Baking the cookies is a chemical change, but some of the ingredients may go through a physical change before entering the oven.
If you like cooking, you may consider yourself to be an amateur chemist, even if you do not know what a stoichiometry is.
Assembling, measuring, and preparing the ingredients for mixing could result in numerous physical changes. Melting solids into liquids, boiling liquids giving off gases, preparing solutions of solids, and color changes are a few of them.
The baking part is where slow, uniform heat is applied to your ingredient mix. (See also - "Is burning a chemical change?")
This is where the real magic occurs as is evident by the wonderful smell coming from the kitchen.
The ingredients undergo a chemical change as a result of the heating to produce a substance that has some attributes of the original ingredients. But this new substance is a cookie, and its qualities are far superior to any of the ingredients on their own.