In the bowl of a stand mixer, whisk together the warm milk, sugar, and active dry yeast. Let it sit for 5 to 10 minutes until it becomes foamy.

Add the egg, melted butter, and salt to the yeast mixture.

Fit the mixer with the dough hook and add the all-purpose flour. Mix on low speed until the flour is incorporated, then increase to medium speed and knead for 8 to 10 minutes until smooth and elastic.

Transfer the dough to a lightly oiled bowl, cover with plastic wrap, and let it rise for 1 to 1.5 hours, or until doubled in size.

Punch down the dough, reshape it, cover, and refrigerate for at least 1 hour or up to 24 hours.

While the dough chills, pound and roll the cold butter into an 8 by 8 inch square.

Roll the chilled dough into a 16 by 8 inch rectangle and place the butter block on one half.

Fold the other half over the butter, seal it, and roll it into a 24-inch long rectangle.

Fold the dough and refrigerate for 30 minutes.

Repeat this rolling and folding process once more, then roll out to a 12 by 18 inch rectangle and sprinkle with mini chocolate chips.

Roll tightly into a log, cut into 12 pieces, and place cut-side up in a greased muffin tin.

Let the cruffins rise for 45 to 60 minutes.

Preheat the oven to 400 degrees F and bake for 15 to 20 minutes until golden brown.

Cool for 5 minutes before transferring to a wire rack and dusting with powdered sugar.