The cookies should not be overly brown or golden. But if they've baked for 20 minutes, they're done. Let them cool slightly on the cookie sheet before you remove them. Also, how do you know when shortbread is cooked?
Saying that it's hard to know when shortbread is ready, they should be light golden brown which isn't all that different to the colour of the dough. Like all biscuits they will also still be soft until cool.
Beside above, does shortbread cookies harden when cooling? Step 3: The Secret to the Absolute Best Shortbread
Instead, chill the dough in the refrigerator for 30 minutes or so (overnight is OK, too). A short stay in the fridge will firm up the cookies and solidify the butter. This will help keep them from spreading too much.
Simply so, should shortbread be soft when it comes out of the oven?
Shortbread should always have a tender, melting texture, but be slightly crisp when you bite into it. It should not generally be damp or wet underneath. The pan is made of metal but also has low sides so should have fairly good heat distribution while the shortbread bakes.
What happens if you put too much butter in shortbread?
Using too much butter will: Cause your cookie to spread out way too much during baking. Cause your cookie to brown.
Related Question Answers
What can go wrong with shortbread?
There are two main things that can go wrong with the shortbread dough (before it's cooked): first, overworking the dough will put the flour's gluten (proteins) into action. Gluten is what stretches out and makes chewy bread or cookies – and you definitely don't want it working on your shortbread. Why did my shortbread melt in the oven?
Cookies spread because the fat in the cookie dough melts in the oven. If there isn't enough flour to hold that melted fat, the cookies will over-spread. Spoon and level that flour or, better yet, weigh your flour. If your cookies are still spreading, add an extra 2 Tablespoons of flour to the cookie dough. Why is my shortbread not crunchy?
If the butter is too hard, it won't easily incorporate into the shortbread mixture and that will result in overworked dough. Dough that has been overworked is a surefire way to get tough shortbread - something no shortbread should ever be. Can you put undercooked shortbread back in the oven?
Problem eight: Once cooled, if I know my biscuits are underbaked can I put them back in the oven? Jo's solution: You can. Also, if you don't eat shortbread within a few days and they go soft, you can refresh them in the oven, too. What do I do if my shortbread is too dry?
So shortbread dough is likely to be somewhat crumbly. But if it's too crumbly, you have basically two choices: you can add more butter (or whatever fat you used in place of butter), or you can add a little liquid. What should the consistency of shortbread dough be?
The cookie dough should be crumbly but hold together when squeezed. Turn the dough out onto a piece of parchment paper and knead lightly until it holds together. Why do you fork shortbread?
Use a fork to prick the dough all over; this allows any steam to escape, and prevents the shortbread from bubbling as it bakes. Why do you put cornstarch in shortbread?
A more frugal alternative -- especially appropriate when baking a Scottish specialty -- is to cut back slightly on your flour and replace it with cornstarch. This reduces the gluten in your cookies just as effectively as using pastry flour or cake flour, giving them the traditional light and friable texture. Should cookies be soft out of the oven?
When a light-colored cookie is done, it should hold its shape. However, it may look a bit puffy or soft in the center, too. This is normal and simply means that the cookie may continue baking on the sheet and rack once removed from the oven. What is the difference between Scottish shortbread and regular shortbread?
Unlike Walkers shortbread cookies where the main ingredient is butter, Scottish cookies may contain vegetable shortening or a blend of butter and vegetable shortening. Therefore, the Scottish cookies have a distinctly different texture (crisper, firmer and crunchier) and flavor. What makes a good shortbread?
Shortbread has so few ingredients that you can't get away with cutting corners; good quality butter and sugar are essential, and plenty of them. Rice flour gives it that special sandy texture that sets it apart from the common biscuit, and a pinch of salt helps to balance that rich, delicious sweetness. 
