Chocolate Fudge one pot

 1 (14-ounce) can sweetened condensed milk 

12 ounces semisweet chocolate, finely chopped 

6 ounces milk chocolate, finely chopped 

⅛ teaspoon fine sea salt 

1½ teaspoons pure vanilla extract 

Add chopped walnuts optional 

Line the bottom and sides of a 9-inch square baking pan with two strips of parchment paper that fit the pan both vertically and horizontally, leaving a 2-inch overhang on all sides. Combine the condensed milk, chocolates, and salt in a heavy-bottomed saucepan. Cook over low heat, stirring, until the chocolate has melted and the mixture becomes thick and shiny, 6 to 7 minutes. Remove from the heat and whisk in the vanilla. Pour the mixture into the prepared pan, smoothing it into the corners with a knife or offset spatula. After a few minutes, take a sharp knife and gently score the fudge into 1-inch pieces. (This will make it easier to cut once it has set.) Let the fudge set at room temperature or in the fridge for at least one hour. Remove the fudge from the pan and cut it into pieces along the scored lines.