1-First Step: Prepare the Toffee Bits Start by combining ¼ cup (56g) unsalted butter, ½ cup (100g) light or dark brown sugar, and ¼ teaspoon fine salt in a small saucepan over medium heat. Cook while whisking often until the mixture reaches 300°F (149°C), about 8-10 minutes; if it separates, remove from heat and whisk until combined. For vegan adaptations, use vegan butter here to keep the toffee bits rich and chewy in your salted toffee espresso blondies.

2-Second Step: Cool and Break the Toffee Pour the toffee onto a parchment-lined baking sheet and spread it thin, then let it cool for 15 minutes. Once cooled, break it into small pieces, making sure to handle it carefully to avoid burns. This step works well for gluten-free versions since no flour is involved, ensuring your salted toffee bars have that perfect crunch.

3-Third Step: Preheat and Prepare the Pan Preheat the oven to 350°F (176°C) and butter and line an 8×8 inch square pan with parchment paper, leaving an overhang for easy removal. For low-calorie options, use a light butter spray to cut down on fat while preparing your salted toffee espresso blondies batter.

4-Fourth Step: Mix the Wet Ingredients In a large bowl, combine ½ cup (113g) melted unsalted butter and 1 cup (200g) packed light or dark brown sugar; whisk until combined, then let cool for 5 minutes. Add 1 whole large egg, 1 large yolk, and 1 teaspoon vanilla paste or extract; whisk until emulsified. For vegan salted toffee espresso blondies, replace eggs with flax eggs to maintain the batter’s smooth texture.

5-Fifth Step: Combine Dry Ingredients In a separate bowl, mix 1 ¼ cup (150g) all-purpose flour, 1 ½ teaspoon fine instant espresso powder, and ½ teaspoon fine salt. Sift the dry ingredients into the wet mixture and stir until only a few flour streaks remain, avoiding overmixing to keep your toffee blondies tender. Use gluten-free flour for adaptations that preserve the espresso blondies’ light structure.

6-Sixth Step: Fold in Add-Ins Gently fold in 4 ounces (113g) roughly chopped semi-sweet or dark chocolate bar and ½ cup (78g) homemade toffee bits, reserving some for topping. This is where you can add low-calorie sugar substitutes if needed, ensuring the flavor of your salted toffee espresso blondies stays balanced.

7-Seventh Step: Bake the Blondies Pour the batter into the prepared pan and sprinkle the reserved chocolate and toffee bits on top. Bake for 20-24 minutes, or until the edges are golden and the center is shiny and slightly puffy; a toothpick should come out with a few moist crumbs. For dietary needs, rotate the pan halfway if using vegan ingredients to ensure even baking in these salted toffee bars.

8-Eighth Step: Cool and Slice Cool completely on a rack before slicing into about 16 pieces (1-inch squares), which takes around 30 minutes. Sprinkle with flaky sea salt before serving, and for low-calorie options, opt for a lighter salt to keep things in check with your salted toffee espresso blondies.