Heat the olive oil in a skillet on medium. Add in the onion and cook down until softened. Next, add in the leek and mushrooms, and cook them off until slightly caramelized.
Add in the minced garlic and Dijon mustard, and stir in. Sprinkle in the flour and mix it through the pan until the vegetables have absorbed it all, then pour in the plant based milk, add in the jar of cannellini beans along with their liquid. Stir well, then add in the bay leaf, fresh thyme and season with sea salt and pepper. Stir again, then leave to cook on a very low heat.
Meanwhile, make the shortcrust pastry by adding the flour, butter, sea salt and water to a food processor with the dough blade attachment. Blend until well combined and a ball of dough forms in the processor bowl.
Remove the dough from the bowl and place on a clean worktop. Smooth into a ball then wrap tightly in clingfilm and place in the fridge to chill for one hour.
Pre-heat the oven to 180 degrees celsius. After one hour, remove the dough from the fridge and place on a lightly floured surface. Using a rolling pin, roll out the dough into a rough circle large enough to completely cover the top of your skillet and is roughly 1-2cm in thickness.
At this point, add the spinach leaves and frozen peas into the pie base mixture, and stir in the parsley.
Carefully fold the pastry dough over the rolling pin, then gently lay it over the top of the pie. Trim the edges of the pie with a blunt knife, crimp around the outside using a fork and make a few holes in the center of the pie for the steam to release while baking. Brush with a little Plant Based milk.
Place in the oven to bake for 35-40 minutes or until the pastry is beautifully baked, flakey and golden in color.
Remove the pie from the oven, allow to cool only for a couple of minutes and serve hot, alongside some steamed greens - enjoy!