Prepare the pan. Line an 8-inch (20 cm) square baking pan with parchment, leaving overhang on two sides to lift the fudge out later. Lightly grease the parchment if you like.

Melt the chocolate with the condensed milk. Add both to a medium saucepan. Warm over low heat, stirring constantly, until smooth and glossy. Do not let it simmer or scorch.

Stir in extras. If using, mix in vanilla and a pinch of salt. Stir until fully combined.

Pour and level. Scrape the mixture into the prepared pan. Smooth the top with a spatula. Tap the pan gently on the counter to release air bubbles.

Chill. Refrigerate uncovered for 2–3 hours, or until firm enough to slice. For faster setting, place in the fridge’s coldest spot.

Slice and serve. Lift the fudge out using the parchment overhang. Use a warm knife (run under hot water and dry) to cut into 1-inch squares.