Pre heat your oven to 200 degrees C.
Place a large oven proof pan or casserole dish over a medium heat & add a little oil.
When the pan is hot sauté the mushrooms for 8-10 minutes, stirring often making sure they’re caramelised & golden. Season with salt & pepper whilst they are cooking.
Stir through the leek, garlic, chilli, tarragon, nutmeg & the bay leaf. Cook for a few more minutes then deglaze with the brandy, if using. Cook for a couple of minutes to cook off the alcohol.
Then stir through the plain flour. Cook the flour out for 1 minute then add the vegetable stock. Stir well with a spatula & bring to a simmer.
Stir through the oat cream & lemon juice. Let the mushroom filling bubble away for 10 minutes.
Meanwhile slice your potatoes fine using a mandolin or sharp knife.
Lay the potato slices on top of the mushroom filling neatly, then drizzle over olive oil & a pinch of seasoning.
Place the pie into the oven to bake for 25 minutes or until the potatoes on top are golden and crisp.
Garnish with thyme and serve.
