Instructions

• Preheat the oven to 350°F. Line an 8-inch square baking dish with parchment paper (leave some overhang for easy removal).
• In a large bowl, whisk the melted unsalted butter and light brown sugar together until completely smooth and no lumps remain.
• Add the egg and whisk until thoroughly combined.
• Add the vanilla extract and the 1/4 teaspoon fleur de sel (or other flaked sea salt) and whisk to incorporate.
• Add the all-purpose flour and baking powder. Using a rubber spatula, stir until most of the dry ingredients are absorbed, scraping the bowl so there are no large pockets of flour.
• Add the semisweet chocolate chips and toffee bits. Stir with the spatula until there are no streaks of flour remaining and the chips and toffee are evenly distributed.
• Turn the thick batter into the prepared pan and spread it into an even layer with the spatula (the batter will be thick, similar to cookie dough).
• Sprinkle a pinch of fleur de sel over the top.
• Bake for 18 to 20 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs attached.
• Cool the blondies completely in the pan before cutting and serving (use the parchment overhang to lift them out if desired).
• Store any leftovers in an airtight container at room temperature for up to 4 days.