In a stand mixer, combine 4 cups of all-purpose flour, 1/4 cup of granulated sugar, 1 tsp of salt, and 2 1/4 tsp of instant yeast. Gradually incorporate 1 1/4 cups of cold whole milk while kneading the mixture on low speed until it is soft and slightly tacky, which should take about 5 minutes. Once mixed, place the dough in the refrigerator for 30 minutes to let it chill and develop flavor.

While the dough is chilling, prepare the butter layer. In a bowl, beat 1 cup of softened unsalted butter with 2 tbsp of all-purpose flour until you achieve a smooth consistency. Shape the mixture into a rectangle, about 7x10 inches, and wrap it in plastic wrap. Chill this butter layer in the fridge for 30 minutes until firm.

After the dough has chilled, roll it out on a lightly floured surface into a larger rectangle, roughly 10x20 inches. Remove the chilled butter layer from the refrigerator and place it in the center of the dough. Fold the dough over the butter, encasing it completely, and seal the edges tightly.

Roll the combined dough into a long rectangle, about 8x24 inches, then fold it into thirds. Wrap the dough in plastic wrap and refrigerate for 30 minutes. Repeat this rolling and folding process two more times for a total of three “turns.”

Once you complete the lamination process, roll the dough out into a large rectangle, about 10x30 inches. Cut the dough into triangles, each having a base of 4 inches. Place a piece of chocolate at the wide end, then roll tightly towards the point of the triangle to form the croissant shape.

Arrange the shaped croissants on lined baking sheets, leaving some space between each one. Cover with a clean kitchen towel and allow to proof at room temperature for about 1 hour, then refrigerate for another hour.

Preheat your oven to 400°F (204°C). Whisk together 1 large egg and 1 tbsp of milk to create an egg wash. Brush the egg wash over the proofed croissants and bake for 20 minutes, or until puffed and deep golden brown.