01 - Line an 8x8-inch baking pan with parchment paper, ensuring the paper extends over the edges to create handles for easy removal later.
02 - Combine granola, honey or maple syrup, and melted coconut oil in a medium bowl. Mix thoroughly 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 your hands 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 incorporated.
05 - Pour the yogurt mixture over the granola base. Use an offset spatula or the back of a spoon to spread it evenly, covering the entire base.
06 - Distribute mixed berries evenly across the yogurt layer. If using, sprinkle chia seeds over the top for additional crunch and nutritional benefits.
07 - Place the pan in the freezer for at least 4 hours, or overnight, until the bars are completely firm and set throughout.
08 - Remove from freezer and lift the slab using the parchment paper overhang. Place on a cutting board and let sit for 5-10 minutes at room temperature to soften slightly for easier slicing. Cut into 12 even bars using a sharp knife.
09 - Transfer bars to an airtight container or freezer-safe bag, separating layers with parchment paper. Store in the freezer for up to 2 months. Serve frozen or allow to thaw for 5 minutes before eating.