They will still be quite gooey inside, but the top will be set, and they should be golden brown at the edges and just beginning to come away from the sides of the ramekins. Leave to cool for 5–10 minutes before serving.
Even if you didn’t add double the amount of milk to the dough, runny dough is often caused by too much liquid. This means that using an ingredient that counteracts that liquid should make your cookie dough thicker than it currently is. The best ingredient to use in this situation is going to be flour.
Cookie dough is much denser and thicker than cake mix and can be rolled into a ball without sticking or falling apart. If your cookie dough does not roll into a ball or falls apart as soon as you attempt to roll it, then it is probably too dry.
Most cookies are still soft when done (they harden as they cool) and will continue to bake on the cookie sheet once removed from the oven. Remove cookies from the cookie sheet as soon as they are firm enough to transfer, using a spatula, to a cooling rack or paper towels to finish cooling.
When cookie dough is sticky, it’s generally because there’s too much moisture. You need to get a good balance of the dry and wet ingredients so that the dough isn’t too wet or too dry. Having cookie dough that’s too wet results in cookies that spread out far too much during baking.
As a general rule of thumb, you should refrigerate cookie dough for at least 30 minutes and up to 24 hours. More than that and you won’t see a noticeable difference in the final product, says Haught Brown.
If the dough seems too soft, chill it for 10 to 15 minutes before portioning. Putting raw dough on cookie sheets still warm from the oven can cause them to begin spreading, leading to burnt edges. Always allow baking sheets to cool completely before adding more batches.
If you find the cookies are greasy you should chill the dough prior to baking.