Salted Caramel Brownies

Preheat oven to 325 degrees. Spray a 13-by-9-inch pan with nonstick baking spray.

In a medium bowl, whisk together flour, salt and baking soda; set aside. 

Melt chocolate and butter, stirring frequently, over low heat in a large saucepan. Remove from heat. Stir in granulated and brown sugars. Cool to room temperature. Whisk in beaten eggs and vanilla. Do not overbeat.

With a spatula, gradually fold in flour mixture until just combined. Pour half into the prepared pan and smooth top with a spatula. Bake for 15 minutes. Cool on a wire rack for 20 minutes.

Increase oven temperature to 350 degrees. Drizzle 3/4 cup caramel sauce over brownies in a zigzag pattern, making sure caramel does not touch the edges of the pan. Spread caramel evenly across brownie layer to within 1/2 inch of edge. Stir remaining brownie batter and drop by spoonfuls over the caramel layer. 

Bake an additional 30 minutes or until toothpick inserted near center comes out clean. Cool 10 minutes. Drizzle with remaining 1/2 cup caramel sauce and sprinkle with fleur de sel. Cool completely before cutting.