Cookies go most smoothly when you set up the ingredients in two little worlds: dry and wet. Put the flour and cornflour together first, then keep the sugar, cooled melted butter and eggs for the wet bowl. That mirrors the card and helps children understand why some ingredients are mixed before everything becomes dough. It also gives you a natural pause to check the butter is cool enough before the eggs appear.
Let the melted butter cool before children whisk it with the eggs. Warm is fine; hot is not. Once the sugar, butter and eggs are in the bowl, whisk until the mixture looks smooth and glossy. If the bowl slides, a damp cloth underneath makes whisking feel far less chaotic.
When the dry ingredients go in, switch the language from whisking to stirring or folding. Children often keep beating hard because that worked in the previous step, but cookie dough needs a slower, heavier mix. Scrape around the sides and bottom of the bowl so no floury pockets are hiding.
The chocolate chip step is a good place to hand ownership back. Folding chips through the dough is satisfying and low-risk, as long as the raw-dough tasting boundary is clear. If you are swapping in raisins, nuts or dried fruit, check allergens and chopping needs before the child is already mid-recipe. Once the dough looks exciting, children are much less patient with adult label-reading.
Chilling is useful even if everyone is impatient. It makes the dough firmer, easier to scoop and less likely to spread too much. Use that hour for cleanup, lining trays and preheating the oven. If waiting is hard, make the next job visible: "When the timer goes, we scoop and space them."
When spooning out, leave real gaps between blobs. The cookies will spread, and two trays are calmer than one overcrowded tray. If your child wants to make them enormous, try giving them a teaspoon or small scoop so the portion size is built into the tool rather than argued about each time.
Bake until the edges are golden but the centres still look soft. That can feel wrong to children, so explain that cookies keep setting as they cool. Leave them on the tray for a few minutes before sharing; it protects fingers, keeps the cookies from falling apart and turns waiting into part of the bake.