Place 13 teaspoons of biscoff cookie butter onto parchment paper and freeze until firm.
Heat your oven to 350°F and prepare two baking sheets with parchment paper.
In a bowl, blend the softened butter and half a cup of biscoff cookie butter until creamy.
Stir in brown sugar and granulated sugar and beat until the mixture looks fluffy.
Add the egg and vanilla extract, mixing thoroughly.
Gently fold in the baking soda, salt, and flour, mixing just until the dough holds together with some flour still visible.
Use a 3-tablespoon scoop to form the dough into large balls.
Remove the frozen biscoff butter balls and press one into each dough ball, covering it completely.
Arrange 6 to 7 cookies per baking sheet and bake for 11 to 13 minutes, edges turning golden.
Warm 2 tablespoons of biscoff cookie butter in the microwave until melted and drizzle over the warm cookies.
Sprinkle a pinch of flaked salt on top and let the cookies cool to set the topping.
