Scoop out teaspoon portions of biscoff spread onto a tray evenly (if weighing, these were 15 grams per each portion) and place in the freezer for at least 20 minutes.
Preheat the oven to 180C/350F and line a baking tray with parchment paper.
Place the butter, brown sugar and 60 grams / ⅓ cup superfine/caster sugar into a bowl and beat on medium until pale and fluffy, approximately 3 minutes with an electric mixer.
Add the egg and vanilla extract and continue to beat until well combined, beating for 1 minute.
Toss in the flour, cocoa powder, baking powder and salt into a separate bowl and stir together.
Add to the wet ingredients and combine on low until no dry portions remain in your bowl.
Place the remaining 50 grams / ¼ cup superfine sugar into a small bowl and set aside on your work surface.
Take a tablespoon portion of the dough and roll into a ball, pressing the dough flat in the palm of your hand to spread out to be approximately 2 x larger than the ball of dough you began with.
Remove the biscoff spread from the freezer and carefully transfer one scoop of biscoff into the center of your cookie dough.
Press the edges of your cookie together, working from the center of your dough outwards, kind of in the shape of an Asian dumpling.
Then roll in the palm of your hand to shape into a ball again.
Toss into the bowl of sugar, coating fully.
Press lightly to flatten and place on your tray.
Repeat with the remaining dough, allowing a 1 ½ inch gap between each cookie.
Bake for 9 minutes or until the exterior has no gloss to its appearance.
Allow to sit on your baking tray for 5 minutes before transferring to a cooling rack.
Allow to cool completely.
Serve with a glass of milk.
Dig in!