Using an electric hand mixer, mix heavy whipping cream in a medium sized bowl until stiff peaks form. Cover bowl with plastic wrap and place in the fridge until ready. (Optional fill an icing bag with large star tip attached, put icing bag into fridge until ready.
Add milk, biscoff spread and frozen yogurt to a blender and blend until mixed thoroughly. Add half of the crushed cookies to the blender and blend for a few seconds.
Divide milkshakes between two 10 oz cups and dollop or pipe the whipped cream on top. Add remaining crushed biscoff cookies to the top.