On a large greased baking sheet arrange six tortillas around the perimeter so that half of each tortilla is hanging over the edge. Fill the middle of the baking sheet with two more tortillas (See step by step photos).
Top with grated cheese followed by sliced avocados and green onions.
Fold the overhanging tortilla into the center to cover the filling and finish off with two more tortillas over the center. Generously brush or spray tortillas with oil and place a second (oiled underneath) baking sheet on top of tortillas to keep tortillas flat while baking. Bake for 20 minutes covered, followed by 5 minutes uncovered or until golden and crispy.
While quesadilla is cooking make the jalapeño ranch by blending all ingredients together using either an immersion blender, blender or food processor.
Cut quesadilla into large squares and serve dipped into jalapeño ranch.