in a large, heavy bottomed pan, heat olive oil on low, add onions, salt and pepper and cook for 5-20mins (the longer the better, but time!)
add garlic if using and fry for 2 mins until fragrant
add mince and fry until cooked
sprinkle over flour and cook until mince is nicely coated. You want to cook for a few mins to cook off the ‘flour’ taste
add carrots, gravy/ stock, bay leaves, marmite and Henderson’s relish, turn heat down to simmer and cook low and slow for up to 40 mins (minimum time 10 mins). Basically stop once it’s thick enough for your liking, it will thicken up a bit in the next step too. Taste and add seasoning if necessary
tip saucepan into a casserole dish, leaving 2-3cm at the top
layer potatoes, overlapping, on top of the stew. Brush with butter then cover and pop in oven at 160/140degreeC fan for 1.5hrs or until potatoes are very soft
brush with more butter then stick under grill for 5-10 mins until potatoes are golden brown
