Cut four strips of parchment paper, each 16 x 4 inches (40 x 10 cm) long. Wrap the outside of four 3/4-cup (180 ml) ramekins with the parchment strips, leaving a border along the top edge (the parchment should be taller than the ramekins). Tape the seams. Place on a baking sheet.
Place the chocolate in a large microwave-safe bowl and melt in the microwave oven. Add the condensed milk and mix well.
In another bowl, whisk the cream and sugar with an electric mixer until stiff peaks form. Using a spatula, gently fold the cream into the chocolate mixture.
Spoon the mixture into the ramekins. It should overfill them by about 1/2 inch (1 cm), but the parchment paper will keep it from spilling. Freeze for 6 hours or until the soufflés are firm to the touch. Remove the paper and serve immediately.