Preheat oven to 350 degrees F.
Use a rolling pin to flatten the slices of Butter Bread. Then use a large cookie cutter or a bowl and a knife to cut a circle from each slice of flattened bread.
Brush both sides of each bread circle with olive oil and bake on a baking sheet for about 5 mins (until golden-brown and toasted), flipping halfway through. Remove from oven and set aside.
In small saucepan, heat the refried beans, stirring occasionally, until thinned and heated through.
Heat oil in a nonstick skillet over medium heat. Cook mushrooms and onions until browned and softened. Add spinach and cook until just wilted; season with salt and pepper. Remove from pan.
In the same pan, add a bit more oil and cook eggs sunny side up, or as desired.
To Assemble Toastadas: Spread refried beans onto the toasted bread circles. Layer on the sautéed mushrooms, onions, and spinach. Top with fried egg. Add sliced jalapeños, avocado, cherry tomatoes, fresh cilantro, green chili salsa, and crumbled queso fresco, along with any other additional toppings as desired, such as hot sauce or sour cream.