Directions:
In the bowl of a stand mixer fitted with the dough hook attachment, combine the water, yeast, sugar, and milk and let it sit until frothy, about 2–3 minutes.
Add the softened butter, the beaten egg, flour, and salt. Stir on low speed until a shaggy dough forms.
If the dough still has some dry spots, stir in another tablespoon of milk.
Increase the speed to medium and knead the dough until it becomes smooth and soft, about 3–4 minutes.
Transfer the dough to an oiled bowl and cover it with a clean kitchen towel.
Let the dough rise at room temperature for 45 minutes.
Gently tip the dough onto a floured surface and roll it into a large rectangle, about 8x14 inches. Rotate the dough so that a short edge of the rectangle is closest to you.
Using a cheese grater, grate the frozen butter and place it onto the bottom half of the dough in an even layer, leaving a ½-inch border along the sides.
Sprinkle about a tablespoon of flour evenly over the butter layer.
Fold the upper half of the dough over the butter layer, and pinch to seal the edges, completely encasing the dough in butter.
Using a floured rolling pin, gently roll the dough into an 8x16-inch rectangle again. (The butter should stay sealed in the dough without breaking through.) The first layer will look a little bumpy, but the surface will get smoother as you continue with the process.
Rotate the dough, so the shorter (8-inch) edge of the rectangle is closest to you, then fold the dough into thirds, like a letter.
Wrap the dough in plastic wrap, set it onto a baking sheet, and let it rest in the refrigerator for 30 minutes.
Repeat steps 10–13 three more times on a clean work surface: rotating, rolling, folding, and resting the dough for 30 minutes in the refrigerator each time.
After the third session of rolling and folding, use a floured rolling pin to roll the folded dough into an 8x16-inch rectangle once more.
Line a baking sheet with parchment paper.
Using a sharp knife, cut the dough into 4 4x8-inch rectangular strips.
Cut each rectangle in half on the diagonal lengthwise to yield 8 triangles that are 4 inches wide at the bottom and 8 inches long.
Begin rolling the 4-inch base up toward the tip, lightly stretching the dough with your fingertips as you roll.
Flip the rolled dough if needed to tuck the point underneath.
Pinch the two edges and curve them inward to make the classic horned crescent shape.
Transfer the shaped cornetto to the prepared baking sheet and shape the remaining triangles.
Cover the baking sheet with plastic wrap and let it proof in the refrigerator for at least 8 hours or overnight.
The next day, preheat the oven to 400 degrees Fahrenheit.
Remove the cornetti from the refrigerator and set them in a cool place while the oven preheats.
Whisk the egg yolk with 1 tablespoon of water to make an egg wash.
Use a pastry brush to lightly coat each cornetto in a thin layer of egg wash.
Bake the cornetti until deeply golden, about 15–18 minutes.
Serve warm or cool completely and store in an airtight container.
Enjoy !
