Line an 8-inch square baking pan with non-stick aluminum foil, extending the foil several inches over the sides and then line the pan in the same way over the other two sides, creating a sling. Press the foil into the edges of the pan so that it fits snugly. This “sling” will help to release the fudge easily from the pan.

Combine maple syrup, sugar, heavy cream and salt in a 3-quart saucepan. Add the candy thermometer and attach it to the side of the pan.

Bring the mixture to a rolling boil over medium-high heat while stirring gently with a whisk. Be very careful not to allow sugar crystals to form on the sides of the pan. Once the mixture comes to a boil, stop stirring and let the mixture boil, unstirred, for 7 to 8 minutes or until the thermometer registers 240 degrees. It will bubble up but will not go over the top of the pan.

Immediately remove the pan from the heat and add the butter but don’t stir it in. Now let the mixture rest until the temperature has dropped to 110 degrees F. This will take some time. Either do something else in the kitchen or set the timer for 10 minute intervals so that you’re keeping a close eye on the temperature. Make sure there is no draft. When the fudge has cooled, add the vanilla and begin to beat the mixture with a heavy wooden spoon. This requires some focused muscle and energy. Pay close attention to the color and texture as you beat. The fudge will go from glossy to creamy and opaque and be more difficult to stir. As soon as the changes start, add the nuts then continue mixing until it is nearly fully opaque.

Immediately pour the fudge into the pan. If it has gotten too thick to pour easily, use a rubber scraper. Gently dab the fudge in the pan with the wooden spoon so that it spreads evenly. Don’t try to even it out as you’ll end up with a mess.

Let the fudge rest for two to three hours, or until it is very firm. Don’t refrigerate until it is firm. Remove the fudge from the pan, using the sling, and wrap it in the foil or with plastic wrap. Chill and then cut it into squares. You can also store it in the refrigerator as a block, and cut pieces off or you can also store it in an air-tight container.

This recipe makes approximately 36 pieces.