Add blueberries, Greek yogurt, milk, honey or maple syrup, vanilla extract, chia seeds if using, and protein powder if using to a blender.Blend until smooth and creamy.
Taste the mixture before freezing. Frozen treats taste slightly less sweet once frozen, so add an extra drizzle of honey or maple syrup if needed.
Pour the blueberry yogurt mixture evenly into popsicle molds, leaving a little space at the top for expansion. Insert popsicle sticks.
Freeze for at least 4–6 hours, or until completely solid.
Run the outside of the popsicle mold under warm water for a few seconds to help release the popsicles. Serve immediately.