Preheat your oven to 400°F. While it heats, prepare your mise en place: measure out the milk, chicken broth, sour cream (making sure it's at room temperature for smooth blending), and all dry spices. Finely chop the green chilis and thinly slice the green onions into 1/8-inch pieces. Have the cooked and cooled shredded chicken ready, and measure out the frozen corn. This prep work ensures the sauce comes together quickly without any scrambling.

Melt the butter in a medium saucepan over medium heat. Once melted and foamy, whisk in the flour and cook for about 1 minute, stirring constantly to create a light roux—this will thicken your sauce and give it body. Gradually whisk in the milk and chicken broth together, then add the sour cream, whisking until completely smooth to avoid lumps. I like to use room temperature sour cream because it blends seamlessly without breaking.

Add the cumin, finely chopped green chilis, chili powder, salt, and black pepper to the saucepan. Reduce heat to medium-low and simmer for 3-5 minutes, stirring occasionally, until the sauce thickens enough to lightly coat the back of a spoon. The sauce will continue to thicken slightly as it cools, so don't over-reduce it. Taste and adjust seasonings as needed—this is your moment to balance the flavors before combining with the chicken.

In a medium bowl, combine the cooked shredded chicken, frozen corn, and sliced green onions. Pour the warm sauce from Step 3 over the chicken mixture and stir until everything is evenly coated and well combined. The filling is now ready to assemble into tacos. I prefer to let the filling rest for a minute so the flavors can meld together before filling the tortillas.

While the filling rests, warm the corn tortillas in a dry skillet over medium-low heat, about 30 seconds per side, until they're pliable and warm. This makes them easier to fold without tearing. Place a warmed tortilla on your work surface, add about 3 tablespoons of the chicken filling mixture down the center, sprinkle with about 1/2 ounce of shredded mozzarella cheese, then fold the tortilla in half to create a taco shape. Arrange the filled tacos seam-side up on a parchment-lined baking sheet as you go.

Place the baking sheet with assembled tacos into the preheated 400°F oven and bake for 12-15 minutes, until the cheese is melted and bubbly and the tortillas have begun to turn golden brown around the edges. Remove from the oven and let cool for 1-2 minutes before serving. The tacos will be hot and the cheese perfectly melted—serve immediately with your favorite toppings like salsa, jalapeños, or additional sour cream if desired.