Heat oven to 180c.
Peel and chop the potatoes, add water to cover, bring to the boil and simmer until cooked. This should take around 15 - 20 minutes.
Grill the sausages until golden brown, this should take around 10 minutes.
Chop each sausage into 4 pieces.
Heat the oil in a pan and lightly sauté the onions, mushrooms and peppers.
Put the sausages and sautéed veg in an ovenproof dish.
Stir through the beans.
Season with salt and pepper.
Stir in the BBQ sauce and chilli powder.
Drain and mash the potatoes.
Put on top of the sausage mix and rough up the top with a fork.
Dot with the butter.
Bake for 20 minutes and serve.
Servings 4