Cut the avocados in half. Scoop the pulp into the work bowl of a food processor. Add the buttermilk, olive oil, chile powder, cumin, salt and pepper. Pulse until smooth, scraping the sides as needed.
In a large bowl, combine the spinach and mustard greens. Add the desired amount of dressing to the greens, tossing gently to coat. Add the tomatoes, cheese, beans, corn and Buttermilk Cornbread. Serve immediately with additional dressing if desired.
Preheat the oven to 425 degrees F. Spray a 9-inch-square baking pan with nonstick cooking spray.
In a large bowl, whisk together the cornmeal mix, buttermilk and egg, whisking until no lumps remain. Pour into the prepared pan. Bake until a wooden pick inserted in the center comes out clean, 15 to 20 minutes. Cool completely in the pan.