Salted Caramel Chocolate Bars

For the shortbread layer:
1. Preheat the oven to 325°F. Line an 8×8-inch baking pan with parchment paper allowing paper to hang over two ends of the pan.
2. In a small mixing bowl, combine the flour, baking powder, and salt. Stir with a fork or whisk, then set aside.
3. In a mixing bowl using an electric mixer, beat the butter and sugar for about 1-2 minutes until well blended. Blend in the dry ingredients, until just incorporated.
4. Press the dough into the baking pan until it is in an even layer over the bottom of the pan. Bake for about 15 minutes or until golden. Remove from oven. Let crust cool completely. If there are any areas that have puffed up, gently press them down with a spoon.

For the salted caramel layer:
1. Combine butter, sugar, corn syrup, and condensed milk in a medium non-reactive saucepan over medium heat.
2. Stir constantly with a whisk, until the butter is melted. Increase the heat to medium-high to bring to a boil.
3. Reduce the heat to a simmer, and continue to stir constantly with a whisk.
4. When the mixture turns a dark amber color and thickens (about 10 minutes, depending on your stove), remove from heat, and add in the salt at the last minute. Give it one more stir to incorporate the salt, then pour the mixture evenly over the shortbread layer, using a spatula to smooth the top. Let it cool, then chill in the refrigerator.

For the dark chocolate layer:
1. Combine the chocolate, corn syrup, and butter in the top of a double boiler (with simmering water in the bottom). Stir until the chocolate is completely melted.
2. Pour evenly over the caramel layer, and use a spatula to smooth the top. Allow it to cool for a few minutes, then sprinkle with fleur de sel.
3. Chill completely, then slice to serve.