Combine the butter, flour, cheese and egg in a bowl, kneading to form a dough. Cover and chill 30 minutes in the fridge. Meanwhile, preheat oven to 180 degrees C and line a baking tray with baking paper.
Roll out the dough and cut into 1cm wide strips. Place on the baking tray.
Whisk the egg yolk with a little milk and brush the strips with it. Sprinkle with coarse sea salt and caraway seeds, then bake 10-15 minutes or until lightly browned.