- Line a 43 x 30-cm (17 X 12-inch) baking sheet with parchment paper, letting the paper hang over two sides. Lightly butter.
- In a saucepan, bring the maple syrup to a boil with the butter, vanilla, and salt. Cook until a candy thermometer reads 146 °C (294 °F). Watch carefully, because the temperature rises quickly at around 130 °C (260 °F). This step must be done quickly. Remove immediately from the heat and stir in the baking soda. Quickly pour onto the baking sheet. With a spatula, thinly spread the maple caramel to about a 30-cm (12-inch) square. Allow to cool completely.
- Cover the surface of the caramel with half the chocolate and sprinkle with half of the pecans. Refrigerate for 15 minutes or until the chocolate is firm. Flip the maple crunch and remove the parchment paper. If the caramel seems to be covered with a thin layer of fat, remove the excess butter with a paper towel. Cover with the remaining chocolate and sprinkle with the remaining pecans. Refrigerate the crunch for about 15 minutes before breaking it into pieces. If necessary, reheat the chocolate for a few seconds in the microwave.
- Keeps in an airtight container at room temperature for about 2 weeks.
Here, it is important to use light maple syrup.