Line a 23 X 13-cm (9 X 5-inch) pan with parchment paper, letting the paper hang over two sides. Butter the other two sides. Set aside.
In a bowl over a double boiler or in the microwave oven, melt the chocolate with the condensed milk and water, stirring until smooth.
Remove the bowl from the double boiler and stir in the nuts. Spread in the pan, pressing with a spatula and fold the parchment paper to cover the fudge. Let cool in the pan. Unmould and cut into cubes. Store in an airtight container in the refrigerator for about 1 month or about 2 weeks at room temperature.
This recipe doubles easily.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.