Preheat oven to 350°F.
Prepare Walnut Chorizo: Place beans in a large bowl and use a potato masher or fork to lightly mash (leave some whole for added texture). Stir in walnuts.
In a small bowl, combine chili powder, Mexican chiles, paprika, cumin, oregano, black pepper, and salt; mix well.
Heat oil in a large skillet over medium. Once hot, add spice mixture and cook 1 minute, until fragrant. Add bean mixture and vinegar; stir well to coat. Cook for 8 to 10 minutes, stirring occasionally, until mixture is golden brown and resembles ground chorizo. Set aside.
Prepare Mexican Casserole: Combine yogurt and taco seasoning in a small bowl; mix well.
Spread 1/2 cup of the salsa in the bottom of a 13x9" or 11x7" baking dish coated with cooking spray. Arrange 8 tortilla halves in the bottom (4 lengthwise and 4 crosswise as shown in the photo collage above). Spread half of the yogurt mixture over tortillas and top with 1 3/4 cups walnut chorizo. Spoon 1 cup salsa overtop, followed by one third of the grated cheese. Repeat exact process with another layer of tortillas, yogurt, chorizo, salsa, and cheese.
Arrange remaining 8 tortilla halves overtop, followed by 1 cup salsa, and remaining one third of cheese. Cover with foil and bake for 35 minutes. Remove foil and bake for an additional 10 minutes, until cheese is melted and golden. Top with cilantro and additional garnishes of choice.