Position racks in the upper and lower thirds of the oven and heat the oven to 300°F. Spray two rimmed baking sheets with vegetable oil spray. In a large bowl, mix the oats, nuts, whole-wheat flour, dry milk powder, and salt. In a medium bowl, combine the maple syrup, oil, and vanilla; stir well. Add the maple syrup mixture to the oats and mix to combine.
Divide the mixture between the two oiled baking sheets, distributing it in 1- to 2-inch clumps. Bake for 20 minutes and then flip the clusters
