Preheat your oven to 350 degrees f. and line a large sheet pan with parchment paper.
In a large mixing bowl, combine the oats, cranberries, seeds, and sea salt.
In a separate bowl, whisk together the butter, maple syrup, mashed banana, eggs, and vanilla.
Pour this wet mixture over the oats and stir until well combined and everything is moist. Allow your mixture to sit for 5 minutes, then give it another stir.
Take a bit less than 1/4 cup of the mixture and drop onto the prepared sheet pan.
Slightly flatten and arrange into desired cookie shapes as they will not spread while baking.
Repeat until all of your mixture is used up.
Bake for 15-18 minutes, just until the tops are slightly golden.
Allow your cookies to cool.
Store your leftover cookies in the refrigerator in an airtight container for a week, or frozen for 2 months.
Enjoy!