Preheat the oven to 400 degrees F. Cut the tortillas into 8 triangles and spread them evenly among 2 baking sheets. Spray with cooking oil, season liberally with salt, and bake until crisp and light golden brown, 5 to 7 minutes. Check the chips at 5 minutes to ensure they don’t burn and remember that you will be baking them more when you melt the cheese later, so you don’t want them too brown. Remove the pan from the oven and let the chips cool and harden on a wire cooling rack while you make the beef. Keep the oven on.
In a large nonstick skillet, heat the olive oil over medium-high heat. Add the mushrooms and onions and cook, stirring frequently, until just beginning to soften, about 2 minutes. Add the ground beef to the pan and cook, crumbling it with a wooden spoon or rubber spatula, until no longer pink. Add the chili powder, cumin, garlic powder, salt, and pepper, and stir to coat the beef and veggies. Add the tomato sauce, stir well to combine, and bring the pan to a simmer. Reduce the heat to low and cook, stirring occasionally, until the mixture has thickened and the flavors have had a chance to blend and intensify, about 10 minutes.
Baking method 1: If you want to layer your nachos: Scatter half of the chips on the baking sheet, spoon half of the beef mixture over the top, followed by half of the cheese. Add the remaining half of the chips, followed by the rest of beef, and finish by sprinkling evenly with the remaining half of the cheese. Bake until the cheese is melted and bubbly, about 10 minutes. Top with sour cream, black olives, fresh cilantro, and sliced jalapeno, and serve!
Baking method 2: If you want to spread them out (to maintain crispy chips): spread the chips among the two baking sheets evenly. Spoon the beef mixture among the chips, trying to spoon beef onto each chip. Don’t worry if some falls on the baking sheets. Sprinkle the cheese evenly among the chips. Bake until the cheese is melted, about 10 minutes. Top with sour cream, black olives, fresh cilantro, and sliced jalapeno, and serve!