Preheat the oven to 350F. Lightly grease a large rectangular baking dish (8.5 X 12.5) and line with a peice of parchment paper so the bars are easier to lift out. (I actually just lined the dish with a full sheet of parchment paper and didnt have to grease)
In a large bowl, mash the banana until smooth. Stir in the vanilla.
Place the rolled oats into a food processor (or blender on the lowest speed) and pulse until the oats are coarsely chopped (but still with lots of texture). Stir oats into the banana mixture. ( I actually just put the whole oats in and added 2 scoops of ground pumkin seed protein powder to obtain a similar texture)
Chop the walnuts and cherries and stir all of the ingredients into the banana-oat mixture until thoroughly combined.
Spoon mixture into prepared dish. Press down until compacted and smooth out with hands until even. Use a pastry roller to smooth out if desired.
Bake for 23-27 minutes (I baked for 25min) until firm and lightly golden along the edge. Place dish on a cooling rack for 10 minutes then carefully slide a knife to loosen the ends and lift out. Place granola slab on a cooling rack until completely cool. (can place in a freezer if impatient)