To make dark chocolate fudge: Line a 9 x 9-inch baking dish with foil. Combine 1 cup semi-sweet chocolate chips and ½ can (7 ounces) sweetened condensed milk in a saucepan and warm over low heat. Stir until smooth and add ½ teaspoon vanilla extract. Spread the mixture out into the prepared pan in a thin layer and chill for 2 hours in the fridge. You will have more fudge than needed for the above recipe, but when is too much fudge a bad thing?