Preheat your oven to 200°C (390°F) and heat 1/2 tablespoon of oil in a large frying pan.
Finely dice the veggies and add the onion, mushrooms and garlic to the frying pan. After they’ve softened slightly, add the rest of the veggies and let them soften too – stirring occasionally – for about 7 minutes.
Chop the potatoes into roughly 2-cm chunks and put them on the stove to boil.
Drain and rinse the can of brown lentils and add them to the frying pan. Along with the tomato paste, soy sauce and maple syrup. Stir so that everything is coated.
In a small bowl whisk together the arrowroot flour with 1.5 cups of water. Once it’s smooth, stir it into the filling mixture and let sit on a low heat for 5 minutes.
Use this time to drain, rinse and mash your potatoes with the vegan butter, nutritional yeast flakes, salt and pepper.
Pop the filling into a casserole dish, spread the mashed potato evenly on top then sprinkle with some extra nutritional yeast, salt and pepper if you’d like.
Put your shepherd’s pie in the oven for approximately 30 minutes or until the potato has started to turn light golden on top. Let it cool down considerably before serving. Enjoy!