01 - Line an 8x8-inch baking dish with parchment paper, allowing the edges to overhang for easy removal.
02 - In a saucepan over medium-low heat, combine the peanut butter and maple syrup. Stir continuously until smooth and warmed through, about 2 to 3 minutes. Remove from heat and stir in the vanilla extract and sea salt.
03 - Gently fold the lightly crushed cornflakes into the peanut butter mixture until evenly coated.
04 - Spread the mixture evenly into the prepared baking dish, pressing it flat with a spatula. Transfer to the freezer for 20 to 30 minutes until firm.
05 - Remove the set mixture from the dish using the parchment overhang and cut into 16 even bars.
06 - Combine the dark chocolate chips and coconut oil in a microwave-safe bowl or double boiler. Heat in 30-second intervals or over simmering water, stirring between intervals, until completely smooth.
07 - Dip each bar into the melted chocolate, turning to coat all sides evenly. Place each coated bar onto a parchment-lined tray.
08 - Refrigerate the coated bars for 15 to 20 minutes, or until the chocolate shell is fully set.
09 - Transfer the bars to an airtight container and store in the refrigerator for up to 2 weeks or in the freezer for up to 3 months.