1. Preheat oven to 350-degrees. In a large oven-proof skillet (I used cast-iron), heat the olive oil. Add the bacon, if using, and onion garlic and chard stems and cook over moderate heat, stirring occasionally, until the stems are softened, about 5 minutes. Add the tomato sauce, dried basil and crushed red pepper and simmer until the sauce is thickened, about 15 minutes. Season with salt and pepper.
2. Meanwhile, in a large pot of salted boiling water, blanch the chard leaves for 3 minutes. Drain and let cook slightly. Squeeze out the excess water. Form the chard leaves into 8 small piles and arrange them in the sauce around the side of the skillet. (I blanched and dried the chard in advance to make things easier--it'll keep for at least 30mins/1 hr).
3. Crack the eggs into the skillet between the piles of chard. Transfer the pan to the oven and bake the eggs for 12 to 15 minutes, until the egg whites are just set and the yolks are slightly runny.
4. Transfer the skillet to a rack and sprinkle the cheese on top. Let stand for 5 minutes. Garnish with basil and serve immediately.
Note: I served with crusty bread which was great for dipping and making sure no sauce went to waste! You can use plain marinara but the arrabiata gave this a nice little kick--highly recommend it. I made without bacon and didn't miss it.