Combine all ingredients in slow cooker and stir until well combined.
Turn on high, uncovered for 1½ hours.
Stir occasionally.
Reduce heat to low, uncovered for 2 hours until crispy and dry.
Spread granola on parchment lined baking sheets to cool completely.
Store in airtight container for up to 3 months. Vacuum seal, dry can or freeze for longer shelf life.