Anna, shortbread is so simple you don't even have to roll it out. Just press it into flat shape.
Traditionally, it's baked in a circle (without a pan) and cut like pie slices, but if you want to cut them in squares for your lembas, just bake it in a square pan (this will keep the edges crisp) or pat it into a square and trim the edges immediately after baking.
There is nothing in it but butter, flour and sugar. Use a recipe with rice flour if you want a bit of crumbliness and one with confectionary sugar (which contains corn starch) for tenderness.
Seriously, you can make up two different batches in 5 minutes and see which one you prefer. Kept in a tin, they will be fine. Really. Since they have a lot of butter, I wouldn't wrap them in tissue immediately as they might leave a grease mark.
TIPS:
Be sure to lightly score the unbaked dough where you want to cut it.
Poke holes in the dough to let out steam.
After baking, CUT into final shape soon. Don't let the baked dough get cold or it will be harder to cut.
Start with this KA recipe:
1 cup (2 sticks) salted butter, at cool room temperature*
1 cup confectioners' sugar
2 teaspoons vanilla extract
1/4 teaspoon almond extract, optional, or the flavor of your choice; eggnog flavor makes a delicious holiday shortbread
2 cups King Arthur Unbleached All-Purpose Flour
*Since butter is such a critical element in these cookies, we recommend you use a top-quality butter. Our test-kitchen choice is Cabot.
INSTRUCTIONS
Preheat the oven to 300°F. Lightly grease two round 9" cake pans. If you worry about the shortbread possibly sticking in your particular pans, line them with parchment, and grease the parchment.
In a medium-sized bowl, beat together the butter, sugar, vanilla, and almond extract, then beat in the flour. The mixture may seem a little dry at first; keep beating till it comes together. If it absolutely won't come together, dribble in up to 1 tablespoon of water, until it does. This is a stiff dough.
Divide the dough in half (if you have a scale, each half will weigh about 10 1/2 ounces), and press each half into one of the prepared pans, smoothing the surface with your fingers, or with a mini rolling pin.
Use a fork to prick the dough all over; this allows any steam to escape, and prevents the shortbread from bubbling as it bakes. Prick the dough in a random pattern, but it looks nicer pricked with some kind of symmetry.
Bake the shortbread until it's a light golden brown across the top surface, and a deeper golden brown around the edges, about 35 minutes.
Remove it from the oven, and immediately turn each shortbread round out onto a clean work surface.
Using a pizza wheel or sharp knife, cut each round into 12 wedges. (Do this while the shortbread is still warm; if you wait until it's cool, it won't cut easily.) Transfer the shortbread wedges to a rack to cool.
https://www.kingarthurflour.com/recipes/shortbread-recipe
