In a medium saucepan, melt 1 cup of unsalted butter over medium heat, stirring constantly for about 5–7 minutes until golden brown.

Combine the browned butter with 1 cup granulated sugar and 1 cup dark brown sugar in a large bowl. Mix until smooth and cool.

In a separate bowl, whisk together 2 cups all-purpose flour, 1 cup bread flour, baking soda, baking powder, and fine sea salt.

Whisk in 2 large eggs and 2 teaspoons vanilla extract to the cooled sugar mixture then gradually add the dry ingredients.

Fold in 1 cup chopped semisweet chocolate and 1 cup toffee bits into the dough.

Wrap the dough in plastic wrap and refrigerate for 24 to 72 hours.

Preheat the oven to 350°F and line baking sheets with parchment. Scoop out 3-tablespoon balls of dough onto the sheets.

Bake for 12–14 minutes until edges are golden brown and centers are slightly soft. Reshape if needed and sprinkle with flaky sea salt.

Cool the cookies on baking sheets for 5 minutes before transferring them to wire racks.