Preheat oven to 350F. Spray two cupcake tins with oil spray
Put pretzels into a food processor and blend until you have a fine flour (need about 2 cups of flour)
Beat together butter and sugar until fluffy. Add pretzel flour and beat until combined and the mixture forms large crumbs
Fill up cupcake tins halfway and press down firmly with the back of a spoon
Bake for 20 minutes, until they start to brown
Let the cookies cool in the pan, then gently lift them out using a sharp knife on the edges to get them loose
If desired, drizzle with melted chocolate and decorate with sprinkles