Step 1

Combine 1/2 cup chicken stock, tomatoes, onion, serrano chile, and garlic in a blender. Blend until smooth. Strain tomato sauce into a bowl and reserve.

Step 2

Heat oil in a saucepan over medium-low heat. Add pasta; cook, stirring constantly, until lightly browned, about 4 minutes. Pour tomato sauce into the saucepan over the noodles; add parsley and remaining chicken stock. Season with salt. Bring to a boil, reduce heat, and simmer until noodles are soft, about 20 minutes. Sprinkle with Cotija cheese.