In a stockpot, heat the olive oil over medium heat. Brown the beef on both sides, for about 3-4 minutes each.  Once the beef is nicely browned, but not cooked through, go ahead and remove it from the pot to a plate or bowl.

In the same pan melt the butter and then add the sliced mushrooms. Stir them around until they start to brown. Next, add the onion, celery, and garlic.

Stir frequently until the vegetables start to soften. Add the flour and stir into the vegetable mixture.

Add the balsamic vinegar and deglaze the pan by scraping up all the browned bits off the bottom using a wooden spoon or spatula.

Add the carrots, fresh thyme, and fresh parsley. Add the browned beef into the pot, including all of the juices collected on the plate or bowl.

Pour in the beef stock, and Worcestershire sauce. Give it all a good stir and then bring the pot to a boil. Once boiling, lower the heat to a simmer and let it all cook together for at least 40-45 minutes or until the sauce has started to thicken (the longer you let it go the thicker the filling will be).

Note- if you are baking to serve this meal right away, take out the pie crust and allow it to come to room temperature while the mixture is simmering. 

Once the filling has thickened, if you are baking this to serve right away, add the peas and the cream.  

Preheat the oven to 400°f. Pour the filling into a 9-inch pie dish that has been lightly sprayed with nonstick cooking spray.

Roll out a refrigerated pre-made 9-inch pie crust.  Using a rolling pin, smooth the pie crust out so there is at least 1-2 inches additional crust over the rim of the pie plate.

Transfer the pie crust and place it on top of the filling.  Fold in the extra crust around the edge.  Crimp the edges of the pie crust with a pinch or a fork depending on your preference.

Place the baking dish on a baking sheet lined with tin foil or parchment paper as the pie might drip during baking.

Bake the pot pie at 400 degrees until the pie is browned on top, about 35-45 minutes. Let it stand for 10 to 15 minutes before serving.