Heat up a frying pan on a medium heat, and add the bacon lardons.
Fry the lardons until golden brown and crispy, then remove from the pan and set aside.
To the same pan, add the oil and butter and allow the butter to melt.
Add the peeled an chopped onion, and fry it until golden.
When the onion is ready, add the peeled and chopped garlic, and mushrooms, and leave everything to cook until the mushrooms have released their liquid and have turned a dark brown colour.
Return the bacon to the pan, give everything a good stir, season to taste with salt and pepper, and garnish with parmesan and parsley.
To make the polenta, pour the water into a pan together with the salt, and bring it to a boil.
Add the cornmeal, and whisk it quickly to avoid any lumps forming.
Keep whisking until you get a thick consistency and the polenta pulls away from the edges of the pan.
Transfer the polenta to a plate and top with the mushroom mixture.
Serve hot!