Prep the pan. Line an 8x8-inch baking pan with parchment, leaving overhang on two sides so you can lift the bars out later. Lightly grease the parchment to prevent sticking.

Crush the cornflakes. Add cornflakes to a large bowl and crush gently with your hands. You want a mix of small flakes and crumbs—not powder. Set aside.

Warm the peanut butter. In a small bowl or the microwave, warm the crunchy peanut butter for 20–30 seconds until loosened and spreadable. This helps it blend smoothly.

Make the syrup. In a medium saucepan, add sugar and corn syrup. Heat over medium, stirring until the sugar dissolves and the mixture starts to bubble. Let it gently simmer for 45–60 seconds—just until slightly thickened. Remove from heat and stir in vanilla and salt.

Combine with peanut butter. Quickly stir the warm peanut butter into the syrup until you have a smooth, glossy mixture. Work fast so it doesn’t set up in the pot.

Fold in the cornflakes. Pour the peanut butter mixture over the crushed cornflakes. Use a spatula to fold until every flake is coated. The mixture will be thick and sticky.

Press into the pan. Transfer the mixture to the lined pan. Press it firmly and evenly into a compact layer. A second sheet of parchment or lightly greased hands make this easy. Aim for a tight pack to get the classic crisp bite.

Chill briefly. Refrigerate the pan for 15–20 minutes to help the layer firm up before adding chocolate.

Melt the chocolate. In a microwave-safe bowl, heat chocolate chips with coconut oil in 20–30 second bursts, stirring between each until smooth. Or melt over a double boiler. Do not overheat.

Top with chocolate. Pour the melted chocolate over the chilled peanut layer and spread into an even coating. Tap the pan on the counter to pop bubbles. Sprinkle with flaky sea salt if you like.

Set and slice. Chill 30–45 minutes, until the chocolate is just set but not rock hard. Lift the slab out with the parchment overhang. Use a warm, sharp knife to cut into bars. Clean and warm the knife between cuts for neat edges.

Let them finish setting. If the bars are still a bit soft, return the cut pieces to the fridge for 10–15 minutes more, or let them firm up at cool room temperature.