Preheat your oven to 375 degrees F.
Add the chicken bouillon powder to a boiling pot of water and cook the elbow macaroni for 6 minutes.
Combine the cheddar, havarti, and gruyere in a large bowl.
Once cooked, drain the macaroni and place it in a cast-iron skillet. Add the butter and stir it in until well combined. Then add the sour cream and half of the cheese mixture.
In a bowl, combine the evaporated milk, heavy cream, eggs, salt, pepper, granulated garlic, paprika, and onion powder. Mix until well combined.
Pour the milk mixture all over the mac and cheese, but don't stir. Just make sure you pour it evenly all over the noodles. Feel free to press the noodles down into the sauce using the back of a spoon.
Top the mac and cheese with the remaining cheese and bake for 30 minutes.
Allow the mac and cheese to sit for 10-15 minutes before serving and enjoy!