Start by adding old-fashioned oats to a food processor or blender. Pulse them a few times until they reach a mill-like consistency.
In a large mixing bowl, combine the pulsed oats, protein powder, vegan chocolate chips, raisins, and ground flax seeds. Use a large spoon to mix everything together thoroughly.
In a separate small mixing bowl, combine the peanut butter, nut milk, and maple syrup. Stir until the mixture is smooth and well combined.
Pour the peanut butter mixture into the oat mixture and stir until everything is thoroughly combined.
Prepare a 9 x 13-inch pan by lining it with parchment paper or lightly greasing it.
Transfer the mixture into the prepared pan and press down firmly and evenly.
Once the mixture is pressed down, cover the pan with a lid or foil. Place it in the refrigerator and let it chill for 2 to 3 hours.
After chilling, remove the pan from the refrigerator. Use a sharp knife to slice the mixture into 12 even bars.
Store the sliced bars in an airtight container in the refrigerator until ready to eat.
