Mix the dry ingredients

• Combine the bread flour, cake flour, salt, milk powder, sugar and yeast in the bowl of a stand mixer.

Add the cold water

• Pour in the cold water so the dough temperature stays around 78 °F after kneading.

Knead the dough

• Mix on low speed until a cohesive dough ball forms.
• Add the softened butter and increase to medium speed.
• Knead until the dough passes the window pane test, about 14 minutes total.

First rise

• Shape the dough into a tight ball and let it rise until doubled in size.

Divide and bench rest

• Weigh out pieces of dough and smooth each into a small ball.
• Let them bench rest so the gluten relaxes.

Cut the cold butter

• Cut the cold butter sticks into chunks, keeping them refrigerated until use.

Shape the rolls

• Roll each piece into a teardrop, then roll it flat while tugging down, then repeat with the top half to form a long isosceles triangle.
• Place a chunk of cold butter at the top and roll the dough down tightly, finishing with the tail end at the bottom.

Final proof

• Let the shaped rolls rise until doubled in size, preheating the oven about 25 minutes into the rise.

Brush and bake

• Brush the rolls with leftover butter.
• Bake until golden.