In a large bowl, combine the oats, coconut flakes, pumpkin seeds, cinnamon and sea salt.
Add the mashed banana and coconut oil into the bowl with the oat mixture. Use a spoon to stir until all is very well combined. The mixture should be evenly coated.
Spread mixture in an even layer on a large baking sheet. Press down slightly and place in oven.
Bake for 45 to 55 minutes, checking and tossing every 15 minutes. Break up large clusters as necessary. Once the granola is evenly browned and no longer feels damp, remove from oven. As it cools it will crisp up even more, so do not over-bake.
Once cooled, store in an airtight container at room temperature for up to one week. Or store in the freezer for a few months.