Cut the butter layer into cubes. Arrange the cubes on a silicone pastry mat that will be 15 cm x 15 cm. Fold the pastry mat over the butter and pound with a rolling pin. The butter layer needs to be an exact 17 cm x 17 cm. Place the butter in the fridge for 30 minutes.
Remove the dough from the fridge and roll out the dough until 26 cm x 26 cm.
Remove the butter layer from the fridge and arrange the butter at a 45 degree angle from the dough. The dough will be able to be stretched over the butter layer to create an envelope. Seal the dough together by gently pressing the dough together.
Roll out the dough with the butter fully enclosed to create a long rectangle of 20 cm x 60 cm. Roll the dough lengthwise so it only grows lengthwise.
Fold the dough to create a letter.
Cover the dough with plastic wrap and place on a plate. Refrigerate the dough for 30 minutes.
Repeat rolling the dough out to 20 cm x 60 cm and folding the dough like a letter. Cover and refrigerate for 30 minutes.
Repeat rolling the dough out to 20 cm x 60 cm and folding the dough like a letter. Cover and refrigerate for overnight.
Make your Danish filling and chill it overnight so it's ready for the morning.