Begin by placing the unsalted butter in a saucepan over medium heat. Allow it to melt completely, stirring occasionally. Keep an eye on it as it starts to foam. In about 5-7 minutes, the butter will turn golden brown, and you'll notice a nutty aroma. Once browned, remove it from the heat and let it cool slightly.
In a separate bowl, whisk together the all-purpose flour, baking soda, baking powder, sea salt, and ground cinnamon. This step ensures that your leavening agents are evenly distributed throughout the flour.
In a large mixing bowl, combine the brown sugar, granulated sugar, and Biscoff cookie butter. Pour in the slightly cooled brown butter and mix until well combined. This mixture should be creamy and smooth.
Crack in the two large eggs and add the pure vanilla extract to the butter-sugar mixture. Beat the mixture on medium speed until it is light and fluffy, which will take about 2-3 minutes.
Gradually add the dry ingredient mixture to the wet ingredients. Use a rubber spatula or wooden spoon to mix until just combined. Be careful not to overmix, as this can lead to tough cookies.
Gently fold in the semi-sweet chocolate chips or chunks until they are evenly distributed throughout the cookie dough.
Cover the mixing bowl with plastic wrap and refrigerate the dough for at least 30 minutes. Chilling the dough helps the cookies maintain their shape and enhances their flavor.
While the dough is chilling, preheat your oven to 350°F (175°C). Line your baking sheet with parchment paper for easy cleanup.
Once the dough is chilled, use a cookie scoop or tablespoon to portion out the dough onto the prepared baking sheet, leaving about 2 inches between each cookie. Sprinkle a pinch of flaky sea salt on top of each cookie before baking.
Place the baking sheet in the preheated oven and bake for 10-12 minutes, or until the edges are lightly golden and the centers still look a bit soft. Remember, the cookies will continue to bake on the sheet after being removed from the oven.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack. This helps them set while maintaining that soft, chewy texture.
