Step 1: Prepare the Pan: Grease the square baking dish with a little butter and line it with wax paper or parchment paper, ensuring the paper hangs over the edges for easy removal of the fudge later.
Step 2: Combine the Ingredients: In the heavy-bottomed saucepan, mix the granulated sugar, milk, unsalted butter, pure maple syrup, and a pinch of salt. Place the pan on medium heat, stirring gently until the sugar dissolves and the butter melts.
Step 3: Cook to Perfection: Attach the candy thermometer to the side of the saucepan and let the mixture come to a gentle boil. Stir the mixture occasionally to prevent sticking and ensure even cooking. Cook until the mixture reaches the soft-ball stage, which is around 235°F to 240°F (112°C to 116°C).
Step 4: Add Flavor and Set: Once the mixture reaches the soft-ball stage, remove the saucepan from the heat. Allow it to cool for a minute, and then add the pure vanilla extract. Using the wooden spoon or spatula, beat the mixture vigorously until it thickens and starts to lose its shine.
Step 5: Pour and Cool: Pour the thickened maple fudge mixture into the prepared baking dish. Smooth the top with the back of the spoon or spatula. Let it cool at room temperature for about an hour before transferring it to the refrigerator. Allow it to chill for a few hours or until set.
Step 6: Slice and Enjoy: Once the fudge has set, remove it from the baking dish using the overhanging paper. Slice it into bite-sized squares and relish each delicious piece.