This granola is extremely crispy, full of clumps, and just a little sweet. It's vegan if you substitute for the buttermilk, gluten-free if you're careful about the source of your oats, and just generally very tasty. This recipe started out as a way to use up overripe bananas, leftover buttermilk, and a jar of chia seeds, but I've been making a batch of it every week for a few months now and I'm not tired of it yet! Toasted pepitas are among my favorite things to eat, so although you can substitute for most of the ingredients here if you have other preferences, I do recommend keeping those in the mix.
Two tips: first, carefully tilted and angled parchment can make a great funnel for pouring granola into a container. Second, parchment can be reused: once I've put away the granola I just fold up the parchment and save it for next week's batch. It can handle multiple reuses! Not infinite, of course; you'll be able to tell when it's getting too ragged, but it's certainly good for a few batches. —summersavory
Mix all the dry ingredients - oats, coconut, pepitas, chia and/or flax - in a large bowl and set aside.
In another bowl, mash the banana well. Add the coconut oil, honey or maple syrup, and buttermilk (or milk or water). If any of those ingredients started out cold, the coconut oil will probably harden on contact; microwave the whole lot until it's liquid again. Stir the wet ingredients together a little but don't worry too much about getting them fully blended.
Add the wet ingredients to the dry ones and mix until the oats etc. are fully moistened. A wooden spoon works well for that, as do a clean pair of hands.
Set the mixture aside to rest for moment while you line a baking sheet with parchment paper and preheat the oven to 350F. When the oven is hot, pour the mixture out onto the baking sheet and press it down firmly so it covers nearly the whole tray in an even, squished-down layer. This is what makes for good clumps later on.
Bake the granola for 40-50 minutes, pulling it out every 10 to stir a little. The first time you take it out you'll have to break up the coherent sheet of oats into whatever size clumps you like; try to flip any large chunks so the other side gets a chance to brown. Make sure to rotate some of the stuff from the edges to the center and vice versa. When the granola is browned enough for your tastes, take it out of the oven and let it cool on the tray. I like it very well done so I go the full 50 minutes, but mileage may vary according to your tastes and your oven. It will crisp up somewhat as it cools, but if you leave any really big, thick chunks they'll be a little gooey in the middle.
Once fully cooled, store the granola in an airtight container. I suspect it'd keep for a while but I never seem to have it around longer than a week. I usually eat it with plain yogurt, and some in my family like to add a bit more honey as well.