In a saucepan, melt the butter over medium heat. Stir continuously until it foams and the milk solids turn golden and nutty. Immediately pour into a bowl and let cool for at least 10–15 minutes.

Preheat your oven to 350°F (175°C). Line an 8x8" pan with parchment paper.

After the brown butter has cooled whisk in the brown sugar until combined.

Add eggs and vanilla extract, and whisk until well combined.

Stir in salt and flour until just combined — do not overmix.

Fold in the toffee pieces evenly.

Pour the batter into your prepared pan and smooth the top.

Bake for 25–28 minutes, or until the edges are golden and a toothpick inserted near the center comes out with moist crumb.

Let blondies cool in the pan for at least 5 mins, then remove from pan and transfer to a cooling rack.

Cool completely before slicing into squares.