Fill a large pasta pot just over half-way with hot water. Add in 2 teaspoons salt, cover the pot, and heat on high on your stove.
Line a dinner plate with two paper towels. Place six strips of bacon on the paper towels and cover them with another paper towel. Microwave the bacon for 90 seconds, or until it is cooked through but not crispy. Dab the bacon with the top paper towel to absorb the grease and set the bacon aside to cool.
Grate your cheeses in a blender, if needed. In a small bowl, crack your eggs and beat them with a fork. Whisk in your black pepper, then your Parmesan and Romano.
When the water on the stove is boiling, add your pasta, stir it in, and lower the heat to medium-high. Leave the pot uncovered and stir it occasionally to prevent sticking. After a few minutes, scoop out a couple ladles of pasta water into a bowl to use for later.
Peel and chop your shallot. In a 10-inch skillet, add your butter and olive oil and heat the pan on medium-high to melt the butter. Add your shallots to the pan and lower the heat to medium. Stir the shallots to coat them with the butter and oil, then let them cook for a few minutes until they are soft. When they're done, turn off the heat and transfer the pan to a cool burner.
Cut your bacon into small pieces using kitchen scissors or a knife.
When the pasta seems like it needs another minute to be al dente, turn off the heat and drain the pasta in a colander in the sink.
Then, return the pasta to your pot on the stove and stir in the shallot mixture (make sure to scrape in all the butter and olive oil from the pan), your egg mixture and the bacon. Turn the heat on low and continue stirring the pasta to allow the egg mixture to come to a safe temperature. When the egg mixture starts to thicken (after a couple minutes or so), turn off the heat.
If serving immediately, you may not need to add any reserved pasta water, because the pasta should be creamy enough. But, if the pasta will sit for a few minutes, you will need to add some of the reserved pasta water to keep the pasta from drying out.
The dish is best eaten right away, but if you have leftovers, add extra pasta water to them and store the pasta in the refrigerator for up to three days. Add a little butter or olive oil to the carbonara when reheating in the microwave.
Shallots look like small, brown onions. When you peel one, you will usually find two purplish bulbs inside. Use both of them.