Blend 450g of dulce de leche, 450g of cream cheese, and 1 pinch of salt until smooth.
Set out 750g of thin chocolate cookies and pour 250ml of milk into a shallow bowl. Dip half of the cookies briefly in the milk, one at a time, and arrange them in an 8 × 12in / 20 × 30cm pan.
Spread with half of the cream cheese mixture. Dip and layer the remaining cookies, then cover with the rest of the mixture.
Refrigerate for at least 2 hours, or overnight. Dust with cocoa powder, scatter with 50g of milk chocolate chips, and cut into squares.
