Line your 9x9-inch square pan with parchment paper, leaving some overhang on the sides. Set the pan aside.
In a heavy-bottomed saucepan, combine 2 cups sugar, 1/2 cup unsalted butter, 1/2 cup heavy cream, and 1/4 cup pure maple syrup. Place the pot over medium heat and stir gently until the butter melts and the sugar dissolves.
Attach your candy thermometer to the saucepan, ensuring it doesn’t touch the bottom. Bring the mixture to a boil without stirring, and cook until it reaches 234°F (soft-ball stage).
Once the mixture hits 234°F, remove it from the heat immediately. Stir in 1 teaspoon vanilla extract and 1/2 teaspoon salt. Let the mixture cool without stirring until it reaches about 110°F, about 10-15 minutes.
After cooling, use a wooden spoon or electric mixer to beat the fudge vigorously until it thickens and loses its glossy sheen, about 5-7 minutes.
Gently fold in 1 cup chopped walnuts until evenly distributed. Pour the fudge into your prepared pan and smooth the top with a spatula.
Let it cool at room temperature until firm, about 2 hours, or refrigerate for 1 hour for quicker setting.
Once fully set, lift the fudge out of the pan using the parchment paper edges. Cut into small squares with a sharp knife and enjoy! Store leftovers in an airtight container.
