Step 1: Brown the butter. In a light-colored saucepan, melt the unsalted butter over medium-low heat. Stir frequently. It will foam, then turn clear, and finally develop nutty brown flecks at the bottom, emitting a rich, nutty aroma. Immediately remove from heat and transfer to a heatproof bowl to stop cooking. Let cool for 10-15 minutes, or until still warm but not hot.
Step 2: Cream butter and sugars. In a large bowl, combine the slightly cooled brown butter with granulated sugar and packed light brown sugar. Beat with an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
Step 3: Add wet ingredients. Beat in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract until fully incorporated.
Step 4: Combine dry ingredients. In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt.
Step 5: Combine wet and dry. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix; stop as soon as no dry streaks of flour remain.
Step 6: Fold in add-ins. Gently fold in the semi-sweet chocolate chips, milk chocolate chips, and English toffee bits until evenly distributed throughout the dough.
Step 7: Chill the dough. Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes. For an even richer flavor and chewier texture, chill for 2-24 hours.
Step 8: Preheat and prepare. When ready to bake, preheat your oven to 375°F (190°C). Line baking sheets with parchment paper or silicone mats.
Step 9: Scoop and bake. Scoop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches between cookies. If desired, press a few extra chocolate chips and toffee bits onto the tops of the dough balls.
Step 10: Bake for 10-12 minutes, or until the edges are golden brown and the centers are still slightly soft. They will continue to set as they cool.
Step 11: Cool. Let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely. Enjoy these incredible cookie exchange recipes!