In a large pot, melt the butter, brown sugar and honey on medium-high heat, mixing constantly, until it's boiling. Lower the heat to low and continue to stir for 3-5 minutes until the mixture thickens and has the consistency of caramel sauce. Remove the pan from the heat and stir in the vanilla extract and salt.
Mix in the quick-cooking oats, Rice Krispies Cereal, and ground flaxseed and mix until fully combined.
Line a 9x12-baking pan with aluminum foil. Spray the foil with coconut oil cooking spray. Then, transfer the oat mixture to the pan. Press firmly with a rubber spatula. Sprinkle the mini chocolate chips on top; press down again until the oats are tightly compacted. Cover with plastic wrap and refrigerate for 2 hours.
Once the bars are cool, remove from the refrigerator. Use the foil overhang to transfer the granola bars to a cutting board. Use a sharp knife and cut into 18 rectangles. Wrap each bar with a tiny sheet of parchment paper. Store in an airtight container in the refrigerator.