Pour one tablespoon of the oil into a large non-stick frying pan and fry the bacon rashers in two batches over a medium heat for two minutes on each side, or until browned and beginning to crisp. Drain on kitchen paper.
While the bacon is frying, separate the sausages, if necessary, and squeeze each one out of its skin. Add the sausagemeat to the frying pan and stir in the sliced onions.
Cook over a medium heat for 10-12 minutes, stirring regularly to break up the sausagemeat and brown the onions. Stir in the paprika and hot smoked paprika and cook for one minute more, stirring constantly. Set aside.
Preheat the oven to 200C/190C (fan)/Gas 6. Lightly butter a shallow two litre/3½ pint ovenproof dish, such as a lasagne dish. Snip the cooled bacon into 3cm/1in lengths with kitchen scissors and set aside.
To make the polenta, pour 1.5 litres/2½ pints of water into a large saucepan and stir in the salt. Bring the boil and stir in the polenta with a wooden spoon. Take off the heat and continue to stir for a further four minutes. You will begin to feel the polenta swell and the mixture getting thicker, but it should remain pourable.
Add the butter and three-quarters of the grated cheese. Stir vigorously until the cheeses melt and the polenta looks creamy. Season with lots of salt and pepper. Pour a third of the polenta into the base of the prepared dish and spread evenly with a rubber spatula. (The polenta will thicken as it cools, so it is important to work fairly quickly.)
Spoon half of the sausagemeat mixture evenly over the top. Scatter with half of the bacon. Pour just half of the remaining polenta over the top of the sausagemeat and bacon and spread to the corners of the dish.
Spoon the rest of the sausage and the bacon pieces on top. Finish with the remaining polenta, but don’t take it quite all the way to the sides, so you can see the sausagemeat mixture peaking from underneath.
Scatter with the reserved cheese and bake for 30 minutes, or until golden-brown and bubbling. Serve with a large mixed salad, tossed with a good dressing.