1. In a bowl, combine the flour, sugar, yeast, and salt. Mix well.
2. Cut the cold butter into small cubes and add it to the flour mixture. Use a pastry cutter or your fingers to work the butter into the flour until you have a coarse, crumbly mixture.
3. Gradually add the cold milk and mix until a dough forms.
4. Turn the dough out onto a floured surface and knead it briefly, just until it comes together.
5. Roll the dough into a rectangle, then fold it into thirds like a letter.
6. Repeat the rolling and folding process two more times.
7. Wrap the dough in plastic wrap and refrigerate for at least 1 hour or overnight.
8. Preheat your oven to 425°F (220°C).
9. Roll out the dough into a large rectangle. Cut it into triangles.