Preheat oven to 350 degrees.
Heat oil in large skillet over medium high heat. Place tortillas, one at a time, in the skillet. Cook 30 seconds and then turn and cook the other side of each tortilla 15 seconds. Using a wide spatula transfer the tortillas to a paper towel as you cook them.
Brown chorizo in a the same pan, remove to paper towels and set aside.
Spray a 9x13 casserole dish with Pam.
Line bottom of the casserole dish with tortillas. Cut each tortilla in half so they'll fit for an even layer.
Top the corn tortillas with the chorizo and grated cheddar and Monterey Jack.
Mix eggs, sour cream and salsa together until well blended; pour this mixture over the shredded cheeses.
Bake uncovered at 350 for 30 - 40 minutes or until set.
Make the Velveeta Queso Topping Sauce: While the casserole is baking, prepare the queso topping. Simply add Velveeta, milk and Salsa to a microwave safe bowl. Microwave in 30 second increments, stirring each 30 seconds, until mixture is hot and smooth.
Serve with Velveeta Queso Sauce. Garnish with chopped chives, cilantro and even black olives for color. A slice of avocado is nice here.