Preheat oven to 300° F. Heat a 10-12-inch oven-proof frying pan over medium heat. Fry the pancetta or bacon in its own fat for 4-5 minutes, until it’s crisp and golden, then remove it to a plate. Add the butter to the pan, then the onion. Turn the heat down to medium-low and stirring occasionally, soften the in the butter for 3-4 minutes. Meanwhile, heat the stock in a small saucepan or microwave. Return the pancetta or bacon to the frying pan and stir in the rice. Move the rice around until all the grains get a good coating of the butter. Add the hot stock to the rice, along with some freshly milled black pepper. Increase the heat under the pan to medium and let it come up to a gentle simmer, then transfer pan to the pre-heated oven, without covering, and allow to bake for 20 minutes. (If using separate dish, remove from oven and add risotto to the dish. Stir once and then bake). When the risotto has baked 20 minutes, remove from oven and gently stir in the Pecorino until well combined, then set the timer for a further 15 minutes baking time. Meanwhile, whisk the egg, egg yolk and crème fraîche together. After the additional 15 minutes bake, remove the risotto from the oven and gently stir in the egg mixture, making sure it is well mixed. You may want to taste and add a bit of salt here, if necessary as well. Leave the risotto to stand for only about 1 to 1 1/2 minutes, by which time the eggs and crème fraîche will have thickened. Leaving the risotto to sit any longer will cause it to get quite thick and more sticky than creamy. Still good, but best eaten fresh from the oven. Serve on warmed plates with some more Pecorino Romano sprinkled over.