Is there a way to roll out dough to an even 5mm thickness? I'm a newbie on making cookies. Thanks!
- Get a straight (not tapered) rolling pin.
- Get 2 long strips of something (cardboard, wood, plastic, etc.) that are each 5mm thick.
- Roll your dough out so it's fairly thin, but more than 5mm thick.
- Place one of your long strips on the left of the dough. Place the other long strip on the right side of the dough. (They're like train tracks, and your rolling pin will be the train!)
- Place your rolling pin on both of them, and roll over the dough a few times. The dough will wind up 5mm thick - just as tall as your two supports.
In supplement to Brett's answer, if you don't have something that is 5mm thick and cannot easily create something (e.g. You don't have a table saw lying around to whip up a couple of wooden rails) that is 5mm thick, consider using a stack of multiple thinner things that are more day-to-day present in a house such as paper or card
If you can find something of reasonable thickness and flexibility (card, for example) that it can be wound round the rolling pin, then don't forget that putting 5mm thick rings on either end of the rolling pin is conceptually the same as putting down 5mm rails for the pin to run on - if you make the ends thicker all the way round such that there is a 5mm gap between the surface and the pin when it's being rolled, it will roll to 5mm thick
If you ant find anything, don't despair; recipes are a guide, and it would be very unlikely that the recipe will fail if you roll your pastry out to 4.9 or 5.1 mm thick, so at the very least you could do what most people would do, and roll it out to somewhere near 5mm freehand, using the rolling pin. If you go too thin, fold it over and have another go