Preheat the oven to 325°F (160°C) and line a baking sheet with parchment paper.
In a medium mixing bowl, combine the rolled oats and flour and stir to blend.
Add the maple syrup, drippy peanut butter, oil, and vanilla extract to the oats and stir until all oats are evenly coated and mixture is uniform.
Spread the mixture in an even layer on the prepared baking sheet, pressing lightly for larger clusters if desired.
Bake for 25–30 minutes, stirring once halfway through if you prefer smaller pieces, until the granola is golden brown.
Remove from the oven and allow the granola to cool in open air for at least 1 hour to develop crunch before storing in an airtight container.