1 (17.25 Ounce) Package Frozen Puff Pastry, Thawed According To Package Instructions
4 Tablespoons Butter, Melted
2 Cups Chopped Yellow Onion
2 Cloves of Garlic Minced
6 Cups Baby Portobello Mushrooms, Sliced
3 Cups Button Mushrooms Sliced
2 Tablespoons Fresh Thyme Leaves, Finely Chopped
2 (8 Ounce) Packages Cream Cheese, Cut Into Cubes, At Room Temperature
½ Cup Sour Cream
Sea Salt And Ground Black Pepper To Taste
1 Large Egg
2 Tablespoons Milk
Step 1 Preheat oven to 400 degrees F (200 degrees C). Lightly grease a 9×13 in. baking pan.
Step 2 Line a 9×13 in pan with 2 sheets of puff pastry rolled to fit.
Step 3 Pre-bake bottom crust for 10-12 minutes and remove from oven.
Step 4 Refrigerate the remaining pastry sheets for at least 30 minutes.
Step 5 Meanwhile, melt the butter in a skillet over medium-high heat. Stir in the onions, and cook until soft and transparent, about 6 minutes. Stir in the mushrooms and thyme, and cook until the mushrooms soften and release their juices, about 6 minutes. Mix the cream cheese and sour cream and garlic into the mushroom mixture, stirring until melted. Season to taste with salt and pepper.
Step 6 Spoon the mushroom mixture into the bottom crust. Roll the remaining pastry to fit the 9×13 Pan. Arrange the remaining pastry on top of the mushroom filling. Crimp the edges if needed
Step 7 Whisk the egg and milk together in a small bowl, and use to brush the top of the Casserole.
Step 8 Bake in preheated oven until the crust is golden brown and the filling is heated through, up to 45 minutes. Check for doneness after 30 minutes. Cool another 30 minutes before serving. Serve with garden salad and lemon vinaigrette. Serves 8-10
Variation: Fold 3 Cups of rotisserie chicken into the mushroom mixture and bake as above.