Instructions:

1. Preparing the velouté sauce:
– In a saucepan over medium heat, melt the butter.
– Stir in the flour and cook for 2 minutes to form a roux.
– Gradually whisk in the chicken or vegetable broth until smooth.
– Allow the sauce to simmer for 5 minutes, stirring occasionally.
– Pour in the heavy cream and continue to simmer for an additional 5 minutes.
– Season with salt and pepper to taste. Set aside.

2. Preparing the filling:
– In a large skillet, melt the butter over medium heat.
– Add the onions and garlic, sauté until translucent and fragrant.
– Toss in the mushrooms and cook until they release their moisture and become tender.
– Sprinkle the flour over the mixture, stirring constantly for about a minute.
– Slowly pour in the chicken broth, stirring to combine and create a creamy base.
– Add the heavy cream and the cooked diced chicken, thyme leaves, salt, and pepper.
– Allow the mixture to simmer for 5-7 minutes until thickened. Remove from heat.

3. Assembling the Bouchee à la Reine:
– Preheat the oven to 400°F (200°C).
– On a floured surface, roll out the puff pastry sheet to a thickness of about 1/8 inch.
– Cut out rounds or squares (around 4-5 inches in diameter) using a cookie cutter or a knife.
– Place the cut pastry pieces on a parchment-lined baking sheet.
– Brush the edges of each piece with the beaten egg wash.
– Spoon a generous amount of the creamy chicken and mushroom filling onto one half of each pastry piece, leaving a small border around the edges.
– Fold the empty half of the pastry over the filling and press the edges to seal.
– Decorate the top of each Bouchee à la Reine with small pastry designs if desired.
– Brush the tops with the remaining egg wash for a beautifully golden crust.

4. Baking and serving:
– Bake the Bouchee à la Reine in the preheated oven for 15-20 minutes or until puffed up and golden brown.
– Allow them to cool slightly before serving to avoid burning your tongue in enthusiasm!
– Spoon the velouté sauce generously over the warm Bouchee à la Reine and enjoy the harmonious combination of flavors and textures.

Tips and Variations:
– To add a burst of freshness, consider adding a small handful of chopped fresh parsley or chives to the filling before assembling.
– For an elegant touch, serve the Bouchee à la Reine with a side of steamed asparagus or sautéed green beans.
– Experiment with different mushrooms like shiitake or cremini to infuse unique flavors into the filling.
– If you prefer a more pronounced herb flavor, swap out the thyme for tarragon or rosemary.

Let the Bouchee à la Reine transport you to a world where indulgence meets comfort. With every bite, savor the history, grace, and culinary prowess that this French classic embodies. Bon appétit!