Prep the pan. Line an 8x8-inch (20x20 cm) pan with parchment, leaving overhang for easy lifting. Lightly grease the sides.

Make the crust. In a bowl, combine almond flour, coconut flour, powdered sweetener, and salt. Stir in melted butter and vanilla until a slightly crumbly dough forms. Press evenly into the lined pan.

Bake the crust. Bake at 350°F (175°C) for 10–12 minutes, until set and lightly golden at the edges. Let cool while you make the caramel.

Start the caramel. In a medium, heavy-bottomed saucepan, melt the butter over medium heat. Add the sweetener and whisk until dissolved. Cook, stirring often, until the mixture turns a deep amber and smells nutty, about 6–8 minutes. Lower the heat if it browns too fast.

Add cream and finish. Carefully whisk in the heavy cream (it will bubble). Cook 2–3 more minutes, stirring, until slightly thickened. Remove from heat and stir in vanilla and salt. Taste and adjust salt if needed. The caramel should coat the back of a spoon.

Layer the caramel. Pour the warm caramel over the cooled crust. Tilt the pan to spread. Chill in the fridge for 30–40 minutes, or until the caramel is set but still slightly soft to the touch.

Melt the chocolate. Place chocolate and coconut oil in a heatproof bowl. Microwave in 20–30 second bursts, stirring between, until smooth. Or melt over a double boiler.

Top with chocolate. Pour the melted chocolate over the caramel and spread evenly. Tap the pan gently to release air bubbles. Sprinkle with flaky sea salt.

Set and slice. Chill for 45–60 minutes, or until the chocolate is firm. Lift the slab out by the parchment. Using a sharp knife warmed under hot water and dried, slice into bars. For clean cuts, score the chocolate first, then press straight down.