Prepare your pie dough. (Try my spelt flour pie crust for a healthier alternative!)
Begin by prepping your ingredients and dicing the onion and mushrooms.
In a medium-sized pan, cook the onion and ground beef until browned. Remove any excess fat.
Add the mushrooms and cook for another minute or two. Remove from heat.
Add the spices, Dijon mustard, lemon juice, salt and pepper and set the beef aside to cool slightly. Taste the mixture now to adjust for seasonings.
In a separate small bowl, whisk 5 large eggs. Add the chopped parsley, salt and pepper, and stir.
Prepare your pie plate and roll out the pie dough for top and bottom. Place the dough in the pie plate.
Stir the eggs into the beef mixture and mix thoroughly. Pour the filling into the pie plate and top with the other half of the rolled out pie dough. Crimp the edges and add a few vents to the top of the pie to allow steam to escape.
Cook in a 400 degree Fahrenheit oven for 35-40 minutes or until the crust is a beautiful golden brown. Check the pie after 20 minutes and rotate the pie dish so the crust will brown evenly. Allow the pie to sit for 10 minutes before slicing. Enjoy!