In a saucepan over medium heat, mix together the evaporated milk, condensed milk, whole milk, and 1 tbsp Biscoff spread until smooth and well combined. Set aside.
Slice the Madeira cake into even, thick pieces and arrange them in a snug layer in a deep serving dish or tray.
Pour the milk mixture evenly over the cake, making sure each slice is thoroughly soaked. Refrigerate for at least 4–6 hours or overnight to allow the cake to absorb the liquid.
In a separate bowl, whisk the double cream with vanilla extract until soft peaks form.
Spread the whipped cream over the soaked cake in an even layer. Drizzle the melted Biscoff spread on top in lines or swirls. Use a toothpick or knife to create a marbled effect if desired.
Chill the assembled cake for another 30 minutes to 1 hour before serving for the best texture.