In a large bowl, mash together black and cannellini beans with a fork, spoon or potato masher.
Heat an electric griddle or skillet over medium heat. Add a bit of butter or olive oil.
Place 2 tortillas down, covering each with a bit of both cheeses, then evenly distribute the mashed bean mixture over top. Place the tortilla on the griddle or skillet, then cover with bean mixture with the remaining cheese and the other tortilla. Cook until the bottom is crispy and golden brown, then gently flip and cook for another 2-3 minutes until crispy and golden.
To make the avocado ranch, combine all ingredients in a food processor and blend until creamy, scraping down the sides occasionally when needed. Taste and season additionally if desired. Store avocado ranch in a seal-tight container for 1-2 days!