Boil the pasta in a large pasta pot to an al dente texture, according to the package directions.
Drain the pasta, return it to the pot, and toss it with olive oil to prevent it from sticking together. Cover the pot and set it aside.
Preheat your oven to 375°F.
Generously grease the wells of two 12-cup standard muffin tins, and set them aside.
To make the cheese sauce, melt the chopped butter in a medium-size, heavy-bottomed saucepan over medium heat.
Add the flour and whisk to combine well. The mixture will clump at first, and then smooth after it cooks for a minute or so. This is the roux that will thicken the cheese sauce.
Cook over medium heat, stirring constantly, until the mixture has just begun to turn a very light-brown color, about 2 minutes.
Add the evaporated milk to the roux very slowly, stirring constantly to break up any lumps that might form.
Add 1 cup of milk, and whisk to combine well.
Bring the mixture to a simmer, and continue to cook, stirring occasionally, until thickened and reduced by about one-quarter, about 7 minutes.
The sauce should coat the back of a spoon.
Remove the saucepan from the heat, add the shredded cheeses, salt, and pepper, and mix to combine. The cheese sauce should be very thickly pourable.
Add the beaten egg to the remaining milk, and pour the mixture into the cheese sauce, mixing constantly.
Pour the hot cheese sauce over the cooked pasta, and stir carefully to coat all of the pasta in the cheese sauce without breaking up the pasta at all.
Fill the prepared wells of the miniature muffin tins just past the top with the macaroni and cheese mixture, and press down carefully but firmly to pack the mixture into the well.
Place the muffin tins, one at a time, in the center of the preheated oven.
Bake for about 15 minutes or until the tops are golden brown.
Remove from the oven and allow to cool in the muffin tins for 5 minutes before running a toothpick around the edge of each muffin well to loosen the cups and popping them out.
Serve warm.