Place the flour, sugar, yeast, and salt in a large bowl and whisk together until combined. Slice the butter into ⅛-inch thick slices and toss in the flour mixture to coat.
Add the milk and stir together until a stiff dough forms.
Wrap the dough tightly in plastic wrap and chill for 1 hour.
On a lightly floured surface, roll the dough into a long rectangle shape.
Fold it into thirds (like a letter), turn 90 degrees, and repeat 3 to 5 more times, or until the dough has large streaks of butter in it but it is smooth and flat. (If at any point the butter starts to feel soft, chill it in the refrigerator or freezer until stiff.)
Wrap tightly and chill for 1 more hour, then roll the dough to a thickness of about ¼-inch.
Cut into ½-inch squares and set aside to chill in the refrigerator.
Melt the white chocolate chips and whisk in the melted butter until combined.
Stir the brown sugar and cinnamon together.
Toss the cubes of pastry dough first in the white chocolate mixture, then the cinnamon sugar, to coat lightly.
Line a muffin pan with tulip papers. Divide the coated dough cubes evenly between each well of the muffin pan, then top with a few pinches of the streusel topping.
Allow the pastries to rise in a warm place for one hour.
Preheat the oven to 375 degrees F.
Remove the plastic wrap and bake until puffed, flaky, and golden brown (approx. 18 to 24 minutes).