Heat evaporated milk over medium/high heat in a small saucepan. Stir in the cornstarch and whisk to combine.
Once simmering (bring to JUST before boil...when it starts bubbling up the sides it's ready), reduce heat to low immediately.
Immediately stir in the cheese in batches, starting with the white american cheese. As you stir in the cheese, increase heat to medium/low and whisk CONSTANTLY while the cheese melts. Once each batch is melted/creamy, add more. Don't stop stirring, you have to whisk the entire time while adding cheese.
Once done with the white American, add in the shredded fontina or mozzarella. Again, whisk CONSTANTLY while the cheese melts, insuring you have a creamy blend. If you prefer the cheese a bit thicker, add a bit more of the mozzarella.
Once all the cheese is melted, stir in the jalapenos, chili powder, nutmeg, red pepper, and salt and pepper. *** (see note)
If you want the queso to be browned like in my pictures, pour the queso into a small nonstick skillet and place in the oven. Broil for 3-4 minutes or until cheese begins to bubble and brown (optional)
Top with cilantro, tomatoes, and more jalapenos if desired.
Serve with tortilla chips and enjoy!