Preheat oven to 400°.

In a medium pot, melt butter on medium-low heat. Add onions, carrots, potatoes, garlic, Old Bay seasoning, and thyme, and cook until onions are translucent, about 10 minutes.

Add the flour, stir to coat vegetables, and cook about 2 minutes. Add white wine first, followed by milk and chicken stock. Decrease heat to low, stirring often, until mixture is thick and creamy.

Add corn and peas, followed by shredded chicken and 1/2 cup grated Parmesan. Mix well and season with salt and pepper to taste.

Pour into your dish of choice; I prefer a large Dutch oven, but these work well as individuals when portioned into medium-sized ramekins. Fill to 3/4 of dish.

Allow to cool slightly while rolling and cutting your puff pastry top.

In a large bowl, combine flour, sugar, and salt.

Use a cheese grater (the side with the largest holes) to grate your butter over the flour mixture. Toss the butter with the flour until butter is completely coated. Drizzle water, 1/3 cup at a time, over the butter-flour mixture, and combine. Add water until the dough starts to clump together. Your dough will be crumbly, and you should still see bits of butter.

Gently knead the dough until you can form a loose square, about 1 inch thick. Wrap in plastic and chill for two hours.

On a lightly floured surface, roll chilled dough into a rectangle 1/2 inch thick. Fold the dough in thirds, like a letter, and rotate 90 degrees. This is called a turn. Repeat this process until you have done 3 total turns.

Fold into thirds once more, then wrap in plastic and chill for at least 4 hours; at this point you can also freeze your dough. (If using frozen dough for pot pie, pull your dough from the freezer into the fridge the night before you plan on using it.)

Pull your puff pastry from the fridge and place it on a lightly floured surface. Use a rolling pin to roll out your dough to 1/4 inch thick. (If you’re using store-bought sheets, there’s no need to roll the dough out any further.)

The beauty of pies is that they can be finished in a multitude of ways. You can use the sheet as a whole, cut to size, and place it over the top of your dish (quick and easy), but I like to go all out and cut different shapes and patterns to make the top more decorative. Get creative—the world is your pot pie!

Once you’ve cut out your puff pastry top, place it over the top of your dish with prepared filling.

Use a pastry brush to evenly brush the egg wash over the top of the puff pastry. Place pie on a baking sheet and bake until crust is deep golden brown, about 45 minutes. Garnish with sprigs of thyme and enjoy immediately.