Chocolate and Caramel Pecan Squares

Preparation

1. Line a 20 cm (8 in) square baking dish with parchment paper, leaving excess paper on each end to make it easier to lift the dessert out.
2. Spread the pecans out in a single layer at the bottom of the dish.
3. Melt the butter with the vanilla in a heavy-bottomed pot, until small bubbles start to form.
4. Add the corn syrup and sugar. Mix well to prevent the sugar from sticking to the bottom of the pot. Cook over medium-low heat for 25 minutes, stirring regularly, until it forms a dark caramel-coloured mixture or until a candy thermometer reads 145°C (290°F). If the caramel sauce starts to separate as it cooks, remove from the heat and add a little hot water and mix well.
5. Spread the caramel sauce out evenly over the pecans. Sprinkle with chopped chocolate and let sit for 5 minutes. Use a spatula to gently spread the chocolate to even out the surface. Sprinkle with fleur de sel, if desired.
6. Let cool completely at room temperature or in the refrigerator. Lift out of the pan using the long ends of the parchment paper. Cut into squares.