Boil Pasta: Bring a large pot of heavily salted water to a boil. Cook the elbow macaroni for exactly 7 minutes (al dente). Drain the pasta, but keep it hot.

Mix Custard: In a large bowl, whisk the 2 eggs until frothy. Whisk in the evaporated milk, a pinch of salt, and a dash of black pepper.

Temper: To prevent the eggs from scrambling, add 1 cup of the hot pasta to the cold egg mixture and whisk rapidly. Add another cup and whisk rapidly. Continue adding the hot pasta 1 cup at a time, stirring quickly, until the milk mixture feels warm.

Add Cheese & Butter: Add the remaining hot pasta into the bowl. Immediately add 4 tablespoons (½ stick) of butter and the entire 16 oz of shredded mild cheddar. Stir continuously until the butter is melted and the cheese is fully incorporated.

Assemble: Pour the mixture into a lightly greased 9x13 inch baking dish. Sprinkle most of the Colby Jack cheese on top, using a spoon to randomly mix it slightly into the pasta layer. Top evenly with the remaining Colby Jack.

Top with Butter: Cut the remaining 4 tablespoons of butter into small pieces and scatter them randomly across the top of the cheese.

Bake: Bake uncovered at 350°F (175°C) for 30 minutes, or until the top is golden and bubbly.

Rest: Remove from the oven and let sit for 10-15 minutes before serving to allow the custard to set.