Spread 1 Tablespoon of Nutella on a Biscoff cookie. Press another Biscoff cookie on top to create a sandwich. Repeat with the remaining Biscoff cookies. Place on a parchment paper lined baking sheet and put in the freezer.
Meanwhile, melt the melting chocolate according to package instructions.
Remove the Biscoff sandwiches from the freezer and dip half in the melted chocolate. Sprinkle some Biscoff crumbs on top, then return to the baking sheet. Place in the fridge until the chocolate has hardened.
Store in an airtight container in the fridge or freezer.