In a medium saucepan, whisk together the evaporated milk, milk, and cornstarch. Then, turn the heat to low-medium.
12 ounces evaporated milk, 1 cup whole milk, 1 tablespoon(s) cornstarch
Add the jalapeños and chili powder. Continue whisking until the liquid begins to steam and bubbles form around the edges of the pan.
4 ounces jalapeños, 1 tsp. chili powder
Drop bits of the American cheese in a little at a time. Whisk between additions, making sure that all the cheese melts before adding more cheese.
8 ounces white American cheese
Once the American cheese has been added, start adding the Monterey jack cheese a little at a time. Whisk between each addition until all the cheese melts.
8 ounces Monterey jack cheese
Taste and add salt and pepper.
salt, Pepper