Arrange a rack in the upper third of the oven and heat the oven to 350°F.
Place 2 ounces cream cheese in a large microwave-safe bowl. Microwave on HIGH until very soft, about 30 seconds. Add 1 1/2 teaspoons taco seasoning, 1/2 teaspoon dried oregano, 1/4 teaspoon kosher salt, and 2 ounces of the shredded Mexican-blend cheese (1/2 cup), and stir to combine.
Drain and rinse 1 can black beans and transfer to the bowl. Drain 1 can corn and 1 can diced tomatoes and add to the bowl. Add 1 can chopped green chiles, and stir to combine.
Transfer the dip into a medium cast-iron skillet or 8x8-inch broiler-safe baking dish and spread into an even layer. Sprinkle with the remaining 4 ounces shredded cheese (1 cup).
Bake until heated through and the cheese is melted, 20 to 30 minutes. Turn the broiler on to HIGH and broil until the cheese browns, 1 to 2 minutes. Top with desired toppings and serve with tortilla chips.
