In a medium saucepan, melt the cubed unsalted butter over medium heat. Continue cooking, swirling occasionally, until it foams and froths. The butter will sputter and crackle. Cook until it becomes fragrant with amber brown bits forming at the bottom of the pan. Immediately remove from heat and pour into a small heatproof bowl. Let cool until just warm, about 20 minutes.

Preheat your oven to 350°F (175°C). Line large baking sheets with nonstick baking mats or parchment paper.

In a small bowl, whisk together the all-purpose flour, baking powder, baking soda, fine sea salt, and old fashioned rolled oats.

In the bowl of an electric mixer, beat the light brown sugar, granulated sugar, and the cooled browned butter until very well combined, about 3 minutes. Beat in the Biscoff spread. Add the large egg and beat until just combined. On low speed, gradually add the dry flour mixture and beat until just combined. Stir in your favorite chocolate chips.

Drop 3-tablespoon sized balls of dough onto the prepared baking sheets, spacing them apart. Bake for 10 to 12 minutes, or until the edges are golden brown. Let cool on a wire rack before devouring.