Instructions

• Preheat the oven to 350°F (175°C). Line an 8x8-inch baking pan with aluminum foil and set aside.
• In a large, microwave-safe bowl, add ½ cup (1 stick) unsalted butter and microwave on high until melted, about 1 minute.
• Reserve a small amount of the melted butter to lightly grease the lined pan, then let the remaining melted butter cool about 1 minute so it is not piping hot before you add the egg.
• Add 1 large egg, 1 cup light brown sugar (packed), 1 tablespoon vanilla extract, and 1 tablespoon instant espresso granules to the cooled melted butter. Whisk until smooth and uniform.
• Add 1 cup all-purpose flour and ½ teaspoon salt to the wet mixture. Stir until just combined, then fold in ¾ cup semi-sweet chocolate chips. Do not overmix.
• Transfer the batter to the prepared pan and smooth the top lightly with a spatula. Bake for 19–22 minutes, or until the top is set and a toothpick inserted in the center comes out clean or with a few moist crumbs. Do not overbake—the blondies will firm up as they cool.
• Remove the pan from the oven and place it on a wire rack. Cool the blondies completely in the pan before frosting.
• For the frosting, melt the other ½ cup unsalted butter in a small saucepan over medium-high heat.
• Add ½ cup light brown sugar (packed), 1 teaspoon vanilla extract, and a pinch of salt (optional) to the melted butter. Whisk until the brown sugar has dissolved.
• Reduce the heat to low and let the mixture simmer very gently for 3 minutes; it should be barely bubbling with a dimpled appearance. There is no need to stir while simmering.
• Remove the saucepan from heat and let the glaze cool in the pan for about 5 minutes until warm (not hot).
• Evenly drizzle the warm glaze over the completely cooled blondies. Allow the frosting to set fully before slicing and serving, about 1 hour.
• Store blondies airtight at room temperature for up to 1 week, or freeze for up to 6 months.