Using a hand or standing mixer, mix the bananas, peanut butter (1 cup), honey (1/4 cup), cinnamon (1 teaspoon, optional), and vanilla extract (1 teaspoon, optional) until very smooth.
Add oats (2 cups) and almonds (1 cup) and mix until combined.
Turn out onto a parchment covered baking dish (about 9x9 inches). Press and flatten with a spatula until evenly distributed.
Bake at 350 degrees for 30 minutes, or until golden brown on edges.
Allow to cool completely before cutting bars.
Store at room temperature for a week or freeze for up to 6 months in an airtight container or wrapped individually in plastic wrap.
Notes
Variations: Add chocolate chips, other spices like nutmeg, or other extracts like almond.
For a nut-free version, use sunflower seed butter instead of peanut butter and use sunflower seeds and/or pumpkin seeds instead of almonds.
If you're gluten-sensitive, make sure to buy gluten-free oats.
If your peanut butter is salt-free, I recommend adding 1/4 teaspoon or so of kosher salt to the mix.