Prep your pan: Line an 8-inch square pan with parchment paper, leaving overhang on two sides for easy lifting. Lightly grease the parchment to prevent sticking.

Make the oat base: In a large bowl, stir together the rolled oats, coconut (if using), and salt. In a small saucepan over low heat, warm the almond butter, honey, and coconut oil just until smooth and pourable. Remove from heat and stir in vanilla.

Combine: Pour the warm mixture over the oats. Mix until every oat looks glossy and evenly coated. If adding mini chocolate chips, let the mixture cool a minute so they don’t melt, then fold them in.

Press the base: Transfer about 2/3 of the oat mixture into the lined pan. Press it down very firmly with the back of a spoon or a flat-bottomed glass. Aim for an even, compact layer so the bars hold together well.

Make the blueberry layer: In a medium bowl, lightly mash the blueberries with a fork. You want some juices released but still a few whole pieces. Stir in chia seeds and lemon zest. Let it sit for 5 minutes to thicken slightly.

Layer it up: Spread the blueberry mixture over the pressed oat base in an even layer. Dollop the remaining oat mixture on top in clusters, then gently press to create a rustic, crumbled top that adheres to the berries.

Chill: Cover and refrigerate for at least 2 hours, or until firm enough to slice cleanly. For faster setting, place in the freezer for 35–45 minutes.

Slice and serve: Use the parchment overhang to lift the slab out. Cut into 12 to 16 bars with a sharp knife. Wipe the knife between cuts for neat edges.