In a large bowl, combine the natural peanut butter and honey or maple syrup. Stir until smooth and creamy.

Add vanilla whey protein powder, rolled oats, and chia seeds. Stir well to distribute evenly. The batter will be thick but pliable.

Fold in the dark chocolate chips if using.

Using a spoon or cookie scoop, portion the mixture into 12 equal-sized bites on a lined baking sheet. Press gently to compact but keep some texture.

Place the tray in the freezer until bites are firm, about 60 minutes.

Transfer frozen bites into a freezer-safe container or zip-top bag. Keep frozen until ready to eat.