01 - Line an 8x8-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal of the frozen bars.
02 - Combine granola, honey or maple syrup, and melted coconut oil in a medium bowl. Mix until all ingredients are evenly coated and the mixture holds together when pressed.
03 - Transfer the granola mixture to the prepared pan. Press firmly and evenly across the bottom using the back of a spoon or spatula to create a compact, uniform base layer.
04 - In a separate bowl, whisk together Greek yogurt, honey or agave syrup, and vanilla extract until completely smooth and well combined.
05 - Pour the yogurt mixture over the granola base. Use a spatula to spread it evenly, covering the entire surface.
06 - Distribute the mixed berries evenly over the yogurt layer. Sprinkle with chia seeds if using for added texture and nutritional benefits.
07 - Place the pan in the freezer for at least 4 hours, or until completely firm throughout. The bars should hold their shape when cut.
08 - Remove the frozen slab from the pan using the parchment paper overhang. Place on a cutting board and let sit for 5-10 minutes to soften slightly before slicing into bars with a sharp knife.
09 - Store bars in an airtight container in the freezer. Serve frozen or allow to thaw for 2-3 minutes before eating for a softer texture.