Preheat the oven to 350°F/180°C and line two baking sheets with parchment.
Freeze the Biscoff spread on a parchment-lined tray for at least 1 hour, until firm.
Beat the butter and both sugars until smooth and creamy. Add the eggs and mix until incorporated.
Stir in the flour, cocoa powder, baking soda, and salt just until a soft dough forms. Cover and refrigerate the dough for 30 minutes to firm.
Divide the dough into 16 equal pieces. Flatten one piece in your palm, place a frozen Biscoff portion in the center, and cover with a second piece of dough; seal the edges and shape into a smooth ball.
Arrange the cookies on the prepared sheets, leaving space for spreading. Bake for 10 minutes, until edges are set and centers are still soft.
Cool on the baking sheet for 10 minutes, then transfer to a wire rack. Serve slightly warm for a molten center.