Preheat oven to 300 degrees F. Line a 9 x 13 baking pan with parchment paper. Set aside.
Pulse 1/2 cup slivered almonds in a food processor until finely ground. You should have a flour like texture. Do not pulse for too long because you will release the oils. You want it to be dry.
In a large bowl, combine ground almonds, oats, whole wheat flour, salt and the remaining slivered almonds. Pour coconut oil evenly over the mixture and stir. Set aside.
Combine maple syrup and brown sugar in a medium saucepan over medium heat. Stir until the sugar dissolves. Remove from the heat and stir in vanilla extract. Pour sugar mixture over the oat mixture and stir until the wet ingredients evenly coat the dry. Break up any lumps. At this point, the mixture will be very sticky.
Press granola mixture into prepared baking pan, flattening the top to make it even. Bake for 40 minutes, rotating the pan every 10 minutes. Remove from heat and let sit for 5 minutes. Cut into squares and then break into smaller cluster pieces - the granola may still be hot so be careful. Place the granola clusters back into the baking pan and bake for an additional 10 minutes at 300 degrees F.
Remove from the oven and let clusters cool completely. Once cool, store in an airtight container.