Mix butter and celery salt. Add flour and beat. Add remaining ingredients.

Form into a smooth dough and make into a long roll. Wrap in greaseproof paper and place in the fridge for a few hours or days.

Cut in very thin slices and cook in a moderate oven.

I would try 180°C for 10-12 minutes. When they come out of the oven, let them cool for a little while so they can crisp up and become wafers.