Prep oven and baking pan: Preheat oven to 350°F (175°C). Line a 9x13-inch metal baking pan with parchment paper, leaving a 2-inch overhang on opposite sides to easily lift the bars later.

Make shortbread crust: In a food processor (or large mixing bowl using a pastry cutter), pulse together flour, granulated sugar, and fine sea salt. Add cold cubed butter and pulse repeatedly until a sandy, crumbly mixture forms that holds together when squeezed firmly in your palm. Press evenly into the bottom of the prepared pan. Bake for 15 to 18 minutes until lightly golden around the edges.

Toast the pecans: While the crust bakes, toast raw pecan halves on a baking sheet at 350°F for 5-6 minutes until fragrant and nutty. Coarsely chop and set aside.

Cook caramel filling: In a medium heavy-bottomed saucepan over medium heat, melt 1/2 cup butter. Stir in dark brown sugar, honey, and heavy cream. Bring mixture to a rolling boil while stirring constantly with a heatproof spatula. Boil gently for 2 to 3 minutes until thickened and glossy. Remove from heat; stir in vanilla, 1/2 tsp fine sea salt, and toasted chopped pecans.

Bake to bubbling perfection: Immediately pour the hot pecan caramel filling over the warm pre-baked shortbread crust, spreading evenly to all edges with a spatula. Return to the oven and bake at 350°F for 18 to 20 minutes until the caramel is vigorously bubbling across the entire surface.

Salt, cool, and slice: Remove pan from oven and immediately shower the bubbling surface with flaky Maldon sea salt. Cool completely in the pan on a wire rack for 2 hours, then chill in the refrigerator for 30 minutes to set the caramel. Use the parchment overhang to lift the slab onto a cutting board, then slice into 16 thick, chewy squares with a sharp chef’s knife.