Warm the olive oil in a large heavy-bottomed pot over medium heat and add the bacon. Sauté until golden brown. Add the shallots and mushrooms and sauté until the shallots are translucent, about 2 minutes. Add the vinegar, cook for 30 seconds, then add the white wine. Cook until the alcohol has evaporated, about 2 minutes. The mushrooms should be moist and there should still be a little liquid in the bottom of the pot.
Toss in the oats, then a ladleful of the caldo and stir with a rubber spatula. As the oats absorb the liquid, add in a bit more just as you would to make a risotto, stirring the whole time. Stirring helps the starch in the oats come together and lends a nice creamy texture to the risotto.
Once the oats are fully cooked through, about 15 minutes, fold in the cheese, then the butter. Adjust the seasoning as needed. Serve with a fried egg, if you like, and a sprinkling of parsley. Think of this as a main course that’s perfect paired with a salad.