If you're making the pie crust, do that first. Mix the flours, salt and sugar in a large bowl. Use a knife to cut the cold butter into the flour until the butter chunks are very small – you can use your fingers to break the butter up into the flour but don't warm it up too much. Once it looks like the texture of small crumbs, stir in the soy milk, starting with 1/2 cup, until it comes together into a nice ball of dough. Do not knead or overwork the dough, or it will lose its flakiness and become tough. Wrap the dough in cling wrap and chill in the fridge for about 1/2 hour while you make the filling.
Make the filling next. In a large pan, heat the olive oil over medium heat, then saute the onions for about 5 minutes until they start to soften and brown. Add the garlic, paprika, thyme, sage, salt and pepper, and stirfry for 1-2 more minutes to wake up the spices.
Next, add the mushrooms, and cook them down to remove most of the water. Then add the plant-based meat and stir well.
Finally, add the water, nutritional yeast, soy sauce, and cornstarch, and mix it all in well. Turn off the heat and add in the greens, which don't need much cooking. Set aside to cool the mixture while you roll out the crust.
Remove the dough from the fridge, cut it into two pieces, and roll each one out on a floured board to a size big enough to cover the entire bottom and sides of a 9" cake pan. Wrap the dough gently over the rolling pin and then unroll it over the pan. Gently press it down into the pan, making sure it gets into all the corners and comes up all the sides.
Scoop the filling into the bottom pie crust, spread it out evenly, then use the rolling pin transfer to lay the second crust on top of the pie. Trim off any excess crust that's hanging off the edges and save this for decorating the top later. Go around the edge of the pie and pinch the edges together so the filling won't seep out, then arrange any bits of leftover dough into a pattern on top – we made a heart with some leaves.
Brush a bit of soy milk over the whole pie. Bake at 400F for 40 minutes, then check to see if it's getting too brown around the edges. If it is, cover it with aluminum foil. Bake for about 15 more minutes until it's nice and golden brown and smells amazing.
Remove from the oven and rest the pie for about 10 minutes before cutting into it. Enjoy your slice of French Canadian heaven!