Heat olive oil in a large oven safe skillet over medium heat (I used my cast iron). Add the onions, carrots, and celery and saute till the veggie start to soften. Add garlic and cook an additional minute.
Next, add the mushrooms, salt, thyme, smoked paprika and pepper to the pan. Stir well and continue cooking till the mushrooms have softened.
Add the tomato paste and the flour to the skillet. Stir and continue to cook the veggies till they're coated and the mixture starts to coats the bottom of the pan. This should take about 2 minutes.
Add the vegetable broth and wine to the pan. Stir to dissolve the flour and tomato paste that has coated the bottom of the pan.
Bring the broth to a simmer. It will have started thickening. Add in the cooked lentils and peas and let them all heat through. Check to see if additional seasoning is needed.
Preheat your oven to 350ºF.
Wash and peel the potatoes and cut them into cubes to cut down on cooking time.
Boil them in salted water till tender. Drain and mash, with a mixer or by hand, the potatoes with the butter and milk till no lumps are left. Taste and add more salt, if needed.
Smooth lentil mixture in the oven safe skillet and top with the mashed potatoes. It is easier to handle the mashed potato when it is still warm. You may not get the potatoes smoothed all across the potatoes, but use a spoon to wok towards the edges.
Bake for around 15 minutes till everything has heated through.
Sprinkle some more freshly cracked black pepper over the top and serve immediately.