Temper the butter block: Remove the butter block from the fridge and let it sit at room temperature for around 10 minutes depending on your kitchen temperature. The butter should feel pliable and smooth — press gently with your finger and it should indent without cracking. Target around 51°F for the butter and 39°F for the dough.
Lock in the butter: Lightly flour your work surface. Remove the dough from the sheet pan — it should already be the right dimensions. Place the butter block in the center of the dough. Cut and fold the dough edges over the butter to fully enclose it, closing the center seam. Press along the surface lightly with a rolling pin to soften and adhere the butter to the dough, flipping and pressing both sides.
First letter fold: Roll the dough out to approximately 24 inches long at 8 mm thickness applying light even pressure throughout — uneven pressure creates uneven lamination. Perform a letter fold — fold the bottom third up, then fold the top third down over it so you have 3 layers stacked. Cover and refrigerate 15 minutes.
Second and third letter folds: Remove from fridge and use a knife to cut along the two folded edges to release tension — these cut edges always go on the sides as you roll, never at the leading edges. Roll out again to the same dimensions and perform another letter fold. Refrigerate 15 minutes. Repeat one more time for a total of 3 letter folds.
Final roll: Roll out to approximately 8-10 mm thickness in a 12x8 inch rectangle. If the dough feels soft refrigerate another 15 minutes before cutting.
Cut the danish: Use a 10 cm circular cutter to punch out 6 circles from the dough, or cut 4x4 inch squares if you prefer cleaner edges or don't have a circular cutter.
Final proof: Place cut dough on a parchment-lined tray. Lightly cover with plastic wrap and let final proof until noticeably puffy and the lamination layers start to visibly separate — about 2-3 hours at room temperature.