01 - In a large mixing bowl, whisk together the flour, instant yeast, sugar, and salt. Pour in the lukewarm water, milk, and melted butter. Stir until a shaggy dough forms and no dry flour remains.
02 - Turn the dough onto a lightly floured surface and knead for 5 to 7 minutes until smooth, elastic, and slightly tacky. Place in a greased bowl, cover with plastic wrap, and let rise in a warm spot for 1 hour or until doubled in volume.
03 - Place the room-temperature butter between two sheets of parchment paper. Using a rolling pin, beat and roll it into a rectangle approximately 6 x 8 inches. Chill in the refrigerator until firm but still pliable.
04 - On a floured work surface, roll the risen dough into a large rectangle about 12 x 20 inches. Place the butter block on one half and fold the other half over to enclose it. Rotate 90 degrees, roll out again to 12 x 20 inches, and fold into thirds like a letter. Wrap tightly and refrigerate for 1 hour.
05 - Remove the dough from the refrigerator. Roll it out once more to 12 x 20 inches and repeat the letter fold. Wrap and refrigerate for at least 1 additional hour to relax the gluten and firm the butter.
06 - Roll the chilled laminated dough into a large rectangle approximately 12 x 20 inches. Using a sharp knife or dough scraper, cut it lengthwise into 12 even strips about 1 inch wide.
07 - Take one strip at a time and gently stretch it if needed. Roll it up tightly from one end to form a spiral log. Using a sharp knife, cut the log in half lengthwise to expose the inner layers.
08 - Twist each half into a loose spiral and coil it into a greased muffin tin cavity with the cut layers facing outward to showcase the flaky laminations. Repeat with all remaining strips.
09 - Cover the muffin tin loosely with a clean kitchen towel or plastic wrap. Let the shaped cruffins rest at room temperature for 45 minutes to 1 hour until visibly puffy and nearly doubled.
10 - Preheat the oven to 400°F. Bake the cruffins on the center rack for 18 to 22 minutes until deeply golden brown and well risen. Rotate the tin halfway through for even coloring.
11 - Allow the cruffins to cool in the tin for 3 to 5 minutes. If desired, roll the warm cruffins in a mixture of cinnamon and sugar until evenly coated. Serve warm or at room temperature.