In a large pot over high heat, add two tablespoons of butter and melt until frothy. Then add the bison stew meat and sear until browned but still pink in the center, about 2-3 minutes. Remove the bison from the pot and set aside. Do not clean the pot.

Add the remaining butter to the pot and melt until frothy. Add the pearl onions and saute until softened, about 5 minutes. Then add the peas, carrots, celery and parsnip. Cook for another 5 minutes then add the mushrooms, garlic, tomato paste, marjoram and red wine. Let the wine simmer off, another 5-10 minutes.

Stir in the Worcestershire sauce and tater tots followed by the beef gravy, broth, thyme, parsley and bay leaves. Return the cooked bison to the pot and stir lightly to incorporate. Cover and simmer for 10-15 minutes, until thickened.

Preheat the oven to 350 F. Thaw one of the puff pastry sheets until pliable but still mostly frozen – about 10 minutes. Leave the other in the freezer while you work. Grease a pie pan with cooking spray. Place the whole sheet of puff pastry into the bottom of the pie dish and press down lightly. Use a fork to poke holes throughout the puff pastry. Bake for 8-10 minutes, until lightly puffed. Remove from the oven – it will deflate as it cools. Do not turn off the oven.

Remove the filling from the stove and cool for 10 minutes. Ladle the filling into the prebaked crust, filling all the way to the top of the pie pan and covering the bottom completely. Cool slightly to set the filling.

While the filling cools, take out the second sheet of puff pastry from the freezer and lightly thaw. Cut into 12 evenly sized slices then arrange the puff pastry slices on top of the filling in an overlapping pattern. Brush the top of the pastry with whisked egg.

Bake until golden brown and bubbling, about 15-20 minutes. Remove from the oven and cool for at least 10 minutes for the filling to set fully. Serve garnished with fresh thyme and enjoy!