Preheat the oven to 300 degrees. Coat a 9x13 baking dish with cooking spray then line with parchment paper.
Combine the oats, almond flour, pecan pieces, sliced almonds, and salt together in a large bowl; mix until well combined.
Combine the coconut oil, maple syrup, and brown sugar together in a small saucepan over medium-high heat, cook until coconut oil melts and the sugar dissolves. Remove from heat, whisk in the vanilla, and pour over oat mixture.
Mix until everything is evenly combined. Pour into the prepared baking dish, using a rubber spatula to firmly press mixture into an even layer in the pan.
Place into the oven to bake for 40 minutes, rotating the pan every 10 minutes to ensure the granola “slab” bakes evenly.
Remove the baking pan from the oven, leaving the oven on. Allow the granola slab cool in the pan for 10 minutes--cooling is crucial!
Carefully lift the granola out of the pan using the parchment overhang on the sides. Being careful, cut into squares, and then break up into smaller cluster pieces.
Place the clusters on a baking sheet lined with parchment paper, then back into the oven to bake for an additional 10 minutes.
Remove the clusters from the oven and allow them to cool completely. Store in an airtight container and enjoy. Side Note: Clusters become crunchier the longer they cool.