Preheat oven to 350°F (175°C). Line a 9×9-inch baking pan with foil or parchment paper and grease lightly.

In a medium saucepan over low heat, melt butter and white chocolate chips together, stirring frequently until smooth. Remove from heat and let cool slightly.

In a large bowl, whisk together flour, sugar, vanilla extract, salt, and eggs until combined.

Stir in the melted white chocolate mixture until smooth and fully incorporated.

Pour batter into prepared pan and spread evenly.

Bake for 20 minutes. Remove from oven and sprinkle toffee bits evenly over the top.

Return to oven and bake an additional 8–12 minutes, until edges are golden brown. The center may look slightly soft but will set as it cools.

Cool completely before slicing. Chill if needed for cleaner cuts.