Once dry, I painted two coats of chalkboard paint into bottom of the tray. (twopurplecouches.com)
Line a baking tray with greaseproof paper and press the dough down firmly into the bottom of the tray. (deliciouslyella.com)
In Greece they usually also add some potato slices in between the vegetables on the tray and then pour a thin layer of tomato passata to cover the bottom of the tray. (greenkitchenstories.com)