Creating your Sheet-Pan Chicken Pot Pie is simple if you follow these steps:

1. Preheat Oven: Preheat your oven to 400°F (200°C).
2. Cook Chicken: In a large skillet, heat a drizzle of olive oil over medium heat. Add the diced chicken and cook until browned and cooked through, about 5-7 minutes. Remove from heat and set aside.
3. Sauté Vegetables: In the same skillet, add diced onions and garlic. Sauté until onions are translucent, about 3-4 minutes.
4. Add Mixed Vegetables: Stir in the mixed vegetables, thyme, rosemary, salt, and pepper. Cook for an additional 3-4 minutes until heated through.
5. Make Sauce: Sprinkle the flour over the mixture and stir to combine. Gradually add the chicken broth and heavy cream, stirring continuously until the sauce thickens, about 3-5 minutes.
6. Combine Ingredients: Return the cooked chicken to the skillet and mix until everything is well combined. Remove from heat.
7. Prepare Sheet Pan: Line a large baking sheet with parchment paper or lightly grease it. Spoon the chicken and vegetable mixture onto the sheet pan, spreading it evenly.
8. Add Pie Crust: Roll out the pie crust over the chicken mixture, pressing the edges to seal. Cut a few slits in the crust to allow steam to escape.
9. Brush with Egg Wash: Brush the top of the crust with the beaten egg to give it a golden finish.
10. Bake: Place the sheet pan in the preheated oven and bake for 30-35 minutes, or until the crust is golden brown and the filling is bubbling.
11. Cool and Serve: Once baked, remove from the oven and let it cool for a few minutes before serving.

These straightforward steps will guide you in creating this incredible dish effortlessly.