Butter a 9-inch square baking dish. For easier removal, line the baking dish with parchment paper or aluminum foil leaving an 1-inch overhand, and then butter the paper or foil. This technique makes it easy to pull the fudge out of the pan in one piece
In a large saucepan over medium heat, combine sugar, butter, maple syrup, milk, and miniature marshmallows; cook, stirring occasionally, until the candy or digital thermometer reaches 235 degrees F. or until it forms a soft ball when a little of the mixture is dropped in cold water. Remove from heat.
Note: The reason that fudge can turn out grainy is that there was still somesugar crystals in the mixture that did not melt. Fudge is what is called a super saturated solution, and one little grain or crystal of sugar or even a bit of dust can cause the sugar to come out of solution and begin to crystallize. To solve the problem place the fudge back into the pan, re-cook it (and during that time to put a lid on the kettle for a minute or so). This washes the sugar crystals off of the side of the pan.
Let cool to 115 degrees F; add walnuts and vanilla extract. With an electric mixer at medium speed, beat until mixture loses its gloss and starts to harden around edge of saucepan. Pour into prepared baking dish. Let cool completely.
When cool, cut into squares.
Yields 36 squares or 1 1/4 pounds.
Maple Nut Fudge Recipe: https://whatscookingamerica.net/Candy/maplenutfudge.htm