How to Make It
In a small saucepan, combine the granulated sugar with 1 tablespoon of water and bring to a boil. Using a wet pastry brush, wash down any crystals on the side of the pan. Boil the syrup over moderately high heat until a deep amber caramel forms, about 5 minutes. Remove from the heat and immediately whisk in the cream, butter and Maldon sea salt. Let the caramel cool to room temperature.
Preheat the oven to 350°. Spray an 8-inch square metal baking pan with nonstick cooking spray and line the pan with parchment paper, allowing 1 inch of overhang on 2 opposite sides; spray the paper. In a small bowl, whisk the flour with the kosher salt and baking powder. In a medium bowl, whisk the butter with the brown sugar until combined, then whisk in the eggs and orange zest. Add the flour mixture and stir until just incorporated.
Spread the batter in the prepared pan in an even layer. Drizzle the caramel over the top, then swirl it decoratively using a toothpick. Bake the blondie for 25 to 30 minutes, until it is golden on top and a toothpick inserted in the center comes out with a few moist crumbs attached. Let cool completely. Lift the blondie out by the overhanging parchment and peel off the paper. Cut into bars and serve.
Maldon sea salt has a great crunch and a remarkably subtle, briny flavor. It is available at most grocery stores and online.