Engineered Cooking

1. Adjust an oven rack to the middle of the oven. Preheat the oven to 350°F. Grease a 9 by 13-in baking pan and line with a parchment sling.

2. In a medium bowl, whisk together the flour and baking powder.

3. In a medium saucepan over medium heat, melt 12 tablespoons of the butter. Brown the butter until it is dark golden brown and giving off a nutty aroma, 2 to 3 minutes. Remove from the heat and add the remaining 4 tablespoons of butter to the pot, swirling the pot until the butter stops foaming. Add the granulated and brown sugars, brewed espresso, vanilla, salt, and espresso grounds, and stir to combine. Let the mixture cool to room temperature. Add the eggs and yolks and whisk until combined. Transfer the mixture to a large bowl. Add the flour mixture and stir until just combined. Add the chopped chocolate, and stir gently.

4. Transfer the batter to the prepared pan, and pat into an even layer. Drizzle the top of the blondies with the caramel. Bake for 16 to 22 minutes, until the blondies are set on the edges and the top is golden brown and just beginning to form cracks. A wooden skewer or toothpick inserted into the blondies should come out slightly wet with clinging crumbs for gooey blondies, and just a couple of crumbs for cakey blondies.

5. Transfer the pan to a wire rack and let cool completely. Use the parchment sling to gently lift the blondies from the pan. Cut them into bars. Store blondies in an airtight container at room temperature for up to 2 days.