Preheat your oven to 400°F (200°C). Measure out skim milk, chicken broth, and sour cream, chopping canned green chilis and finely slicing green onions.

In a saucepan over medium heat, melt unsalted butter, whisk in flour to form a roux, and gradually add milk and broth, whisking to prevent lumps.

Stir in sour cream, cumin, chili powder, salt, and pepper; let simmer for 3-5 minutes until thickened.

In a large bowl, combine shredded chicken, frozen corn, and green onions. Pour warm sauce over, folding gently to combine.

Warm corn tortillas in a skillet for 30 seconds per side, keeping them covered with a towel.

Fill each tortilla with approximately 3 tablespoons of the chicken mixture, sprinkle mozzarella cheese, fold, and place on a baking sheet.

Bake in preheated oven for 12-15 minutes until cheese is bubbly and tortillas are golden brown.

Allow to cool for a few minutes before serving with toppings.