Heat up a large non-stick pan to medium heat and add your olive oil. Add in minced onion and mushrooms. Cook for 5-8 minutes or until onions become translucent.
Add lentils, quinoa and all of your spices. Cover with water (about 4 cups). Bring to a simmer then cover with a lid. Let simmer for 10-15 minutes or until the your mixture thickens. You need to allow the quinoa and lentils to absorb all the excess moisture.
Turn off the heat, and add in your ketchup. Stir until well combined. Let your filling cool down for 15 minutes.
Preheat your oven at 375F.
On a lightly floured surface, roll out half of your puff pastry dough. Prep a 9x9 pie dish by oiling it and dusting with flour. Place rolled dough into pie dish. Scoop up your filling and place it evenly in your pie dish. Spread the filling carefully to make sure it's evenly distributed.
Using a brush, lightly dab the outer edges of your pie crust with water to help seal the pie.
Roll out the other half of your pastry dough. Using a sharp knife, score your dough like the picture above shows. Place dough on top of your pie dish and gently seal the edges by pressing a fork all around the sides of your pie dish.
Mix 1 tbsp of maple syrup with 3 tbsp of non-dairy milk and brush the top of your pie with the mixture.
Bake for 20 to 25 minutes at 375F, or until your pie gets golden brown. Remove from oven and let your pie cool down for about 20 minutes before cutting in. Serve with a dollop of ketchup and enjoy <3