Heat oven to 400F.
In a medium size bowl, mix black beans, refried beans and corn
Grease a 9 x 13" casserole dish with extra virgin olive oil.
Layer half the bean and corn mixture, then top with 1/3rd of the salsa, and 1/3rd the shreds.
Top with 3 tortillas.
Repeat the previous two steps.
Top with the remaining salsa and then shreds.
Cover the dish with tin foil and cook for 25 minutes or until the shreds are melted.
Allow to cool for 7-10 minutes before serving.