Preheat your oven to 200℃.
Chop your onions and garlic, 3 seconds, speed 5. Scrape down the sides and cook 5 minutes, temp 100, speed 1 in a little olive oil.
Add the carrots, zucchini, celery, and process 10 seconds, speed 4.
Now add the sliced mushrooms (I don't like to process them, but you can if you prefer), lentils, tomatoes, stock, rosemary, paprika and seasoning. Cook 10 minutes, temp 100, reverse speed 1.
Add the cornflour/water mixture and cook 5 minutes, temp 100, reverse speed 1. Pour into an oven proof dish and top with the diced potato (and optional cheese and seeds). Stud with any extra rosemary sprigs if you like.
Bake for 20-30 minutes or until the potato is golden and cooked through.
Note - you can top with traditional mashed potato if you like. I'm a lazy, time-poor cook and always looking for shortcuts in the kitchen (and ways to reduce washing up)! This is one saves time and washing, but I don't think alters the taste too much - in fact, I love the crispy baked spuds on top.