Preheat oven to 275 degrees F.
Place oats in a large bowl. Combine honey and peanut butter in a liquid measuring cup. Heat in the microwave for about 45 seconds, until the peanut butter starts to melt. Whisk peanut butter and honey to blend. Add in vanilla and whisk to incorporate.
Pour the peanut butter mixture over the oats and stir until well combined. Spread granola in an even layer on a rimmed baking sheet (line the baking sheet with parchment paper for easy clean up). Bake for 20 minutes, stir, and then press granola into an even layer on the baking sheet. Bake 10-15 minutes more until granola becomes light golden brown.
Let cool completely on baking sheet. The granola will become crisp as it cools. Store granola in an airtight container for up to two weeks.
For 20 servings: 260 kcals, 10 g total fat, 0mg cholesterol, 15 mg sodium, 36 g carb, 5 g fiber, 7 g sugar, 10 g protein.