In a large bowl, combine the warm milk (105-110°F), yeast, and sugar, then let sit for 5 minutes until foamy—this activates the yeast and ensures proper rise. Add the softened butter, salt, and 2 cups of flour, beating for 2 minutes to develop gluten structure. Gradually mix in the remaining flour and vanilla extract until a soft dough forms, then knead for 5 minutes until smooth and elastic. Transfer the dough to an oiled bowl, cover with a damp cloth, and let rise for 1.5–2 hours at room temperature until doubled in size—this first rise develops flavor and builds strength in the dough for lamination.

After the first rise, flatten the dough into a 10x14-inch rectangle on a parchment-lined baking sheet, then cover and chill for 20 minutes to firm up—this makes lamination easier. Place thin slices of the 3/4 cup unsalted butter down the center third of the dough and fold the sides over like a letter envelope, sealing the edges. Roll the dough out to a 9x12-inch rectangle, then fold into thirds (like a letter), rotate 90 degrees, and chill for 20 minutes. Repeat this fold-and-chill process two more times—each fold creates more butter layers for that classic croissant texture. After the final fold and chill, roll out one last time into a 9x12-inch rectangle. I find that keeping the dough and butter cold throughout this process prevents the butter from melting into the dough, which is essential for achieving those distinct, flaky layers.

Roll the laminated dough into a tight log, then cut it into 5 equal pieces using a sharp knife with a gentle sawing motion—this preserves the layers you've built. Place the pieces cut-side up in a greased loaf pan, spacing them evenly so they have room to expand. Cover the pan with a damp cloth and let the dough rise for 45–60 minutes at room temperature until the pieces puff up and fill the pan. While the dough rises, preheat your oven to 350°F about 15 minutes before baking is complete.

In a small bowl, whisk together the egg and water to create a light egg wash. Gently brush this mixture over the top of the risen dough pieces, coating evenly for a golden, shiny crust. Place the loaf pan in the preheated 350°F oven and bake for 25 minutes, then cover the top loosely with foil to prevent the crust from browning too darkly. Continue baking for another 35 minutes (about 1 hour total) until the loaf is deeply golden and sounds hollow when tapped on the bottom.

Remove the loaf from the oven and let it cool in the pan for 30 minutes—this allows the crumb to set without becoming dry. Carefully turn the loaf out onto a wire rack and let it cool for another 15 minutes before slicing. I recommend waiting until the loaf cools completely before slicing to prevent the steam from collapsing those delicate layers you worked so hard to create.