In a bowl, combine flour, sugar, salt, and yeast.
In a separate bowl, warm the milk and water; then mix with dry ingredients.
Add softened butter and egg to the mixture, then knead until smooth.
Cover the dough and let it rise in a warm place for 1 hour.
Roll out the dough into a rectangle on a floured surface.
Fold the dough into thirds, then roll it out again; repeat this twice.
Chill the dough for 30 minutes in the refrigerator.
Cut the dough into triangles, placing chocolate at the base.
Roll each triangle tightly towards the tip to form a croissant shape.
Place on a baking sheet, cover, and let rise for 30 minutes.
Preheat the oven to 375°F (190°C) and brush croissants with egg wash before baking.
Bake for 20-25 minutes until golden brown.