Spray a 9x13-inch baking dish with cooking spray. Preheat the oven to 350°F.
Use a large mixing bowl to combine the hash browns and 1 tablespoon of the Taco seasoning. Toss until evenly coated, then gently press the mixture into the baking dish.
Heat a 10-inch skillet over medium-high heat. Spray with cooking spray and add the chorizo (sausage). Cook for 5-7 minutes or until cooked through, drain.
While the chorizo is cooking, in a medium mixing bowl, beat the eggs, milk, salt, pepper, and the remaining taco seasoning. Once the eggs have been fully beaten stir in the shredded cheese.
Stir in the salsa. Once the chorizo has been cooked and drained, add it to the egg mixture.
Pour the chorizo/egg mixture over the hash browns in the baking pan.
Bake, uncovered, for about 40 minutes, or until the egg center has cooked through.
Allow the casserole to cool and set for about 10 minutes before serving.