Line an angular form (approx. 15 x 25 cm) with foil. Cut marshmallows into pieces. Chop nuts and chocolate coating separately. Dice nougat and butter. Melt chocolate, nougat and butter in a hot water bath while stirring.
Fold in nuts and marshmallows. Pour in the couverture mixture, chill for at least 3 hours.
Remove the chocolate from the mould with the foil and remove the foil. Cut the chocolate confectionery into approx. 15 cubes (approx. 5 x 5 cm). Store in a cool and dry place.