Mix the first 5 ingredients well and press them into a flat baking dish lined with baking paper.
Combine powdered sugar, lemon juice and butter well and spread on the prepared base. Put in a cool place. After approx. 10 - 20 minutes, cut into approx. 18 small rectangles.
Tip: Icing Sugar is powdered sugar that is mixed with a little cornstarch and thus binds well.
Depending on your needs, melted white chocolate can be poured over the lemon slices.