Cream the butter with the sugar, then add the egg and whisk.
Add the flours, baking powder and salt and mix well.
Knead until you have a dough, then wrap it in cling film and leave to rest in the fridge for at least 40 minutes.
Knead the dough, roll out half the dough and cut out 6 cm diameter disks; line the previously buttered muffin moulds and press down the sides to create the edges; punch holes in the bottom and place some dried beans on top.
Bake at 180 degrees for 15 minutes. Knead the remaining dough into discs of about 4 cm in diameter and bake at 180 degrees for 15 minutes (you can also bake them together with the previous ones).