Sharp Cheddar and Gruyere Mac and Cheese

I am notorious for throwing together a homemade mac and cheese with random cheese that I have on hand.  Some are winners and some are just okay.  This one is definitely one I will be making again.  I have used this same milk/butter/egg/flour combo a few times before.  I like it because it creates a great base for the cheese.  You can substitute other cheeses, but I like to make sure that at least one of them is on the stronger side.  I like cheese any cheese...YUM!

Ingredients:

• 1 1/2 Cups of Sharp Cheddar
• 1 1/2 Cups of Guyere
• 12 oz of Pasta cooked al dente (I used medium shells)
• 3 Tablespoons Butter
• 3 Tablespoons Flour
• 1 teaspoon Ground Mustard
• 1/4 Cup Heavy Cream
• 1 1/2 Cups Milk (I used 1%)
• 1 Egg
• Salt and Pepper to taste

While the water for the pasta is coming to a boil I shred the cheese and gather and measure my ingredients because this is one of those recipes that the last 5 minutes is when it all comes together and you can't be scrambling for things.  

Once the pasta is cooked and drained, set it aside.  In the pot you boiled the pasta in melt the butter.  Once the butter is melted whisk in the flour.  Whisk continuously over medium-low heat for about 3 minutes, don't let it burn.  Slowly add the milk, heavy cream, and ground mustard to the butter/flour mixture.  Continue whisking until sauce thickens.  This will take about 5 minutes.  Reduce heat to low.  The next step is a little (just a little) tricky.  Remove about 1/4 cup of the sauce mix.  Gradually whisk the sauce mix into the bowl with the beaten egg.  Make sure you do it slowly so that you don't cook the egg.  Pour the egg mixture into the sauce mixture, mix well.  Next, add the shredded cheese, salt, and pepper.  Mix until cheese is melted.  Last add the cooked macaroni and stir.