Chicken Pot Pie

adapted from Martha Stewart Living ( serves 8 )
Ingredients: 6 tablespoons butter, salted or unsalted
1 large onion, chopped
1 1/2 pounds potatoes, peeled and cut into approx. 1′′ cubes 1 pound (about 6 medium) carrots, cut into approx. 1′′ pieces 10-12 oz. mushrooms, sliced
1/2 cup cognac (I use extra chicken stock)
6 tablespoons all-purpose flour
2 cups chicken stock
1 cup milk
5 cups chicken, cooked (roasted or poached)
1 cup fresh or frozen green peas
5 teaspoons dried parsley
2 1/2 teaspoon dried thyme
1/2 teaspoon dried sage
3 teaspoon salt
1 teaspoon black pepper (I don’t measure the seasonings and am generally heavy handed with them)
1 sheet frozen puff pasty, thawed (I use an easy pie crust recipe)
1 egg yolk + 1 teaspoon water for egg wash

Preparation Instructions: - Preheat oven to 425°F. (If making ahead skip this step.) - In a stock pot or dutch oven, melt the butter over medium-high heat.- Add onion, potatoes, carrots and cook, stirring occasionally, until tender, about 10-12 minutes. - Add cognac, and combine. - Stir in flour and cook for about 1 minute until combined well. - Add chicken stock and milk. Combine well and bring to a simmer for about 2-minutes, stirring until mixture thickens.
- Add chicken, peas, parsley, thyme, sage, salt and pepper, and combine well. - Transfer mixture to preferred serving vessel. Or if preparing ahead, let cool and refrigerate to re-heat later. - When ready to bake, whisk together the egg yolk and 1 teaspoon of water. - Cut thawed puff pasty 1′′ larger in diameter than the chosen serving dish/vessel, and cut out a 1/2- 1′′ hole in center for venting. - Center cut puff pastry over dish and crimp down around edge of dish to seal. - Brush top of pastry with egg wash. - Bake in 425°F oven on baking sheet for 10 minutes, then cover lightly with aluminum foil and continue baking for another 20-25 minutes.