1 tbsp unsalted butter
500ml heavy/35% cream
500ml maple syrup
100h granulated sugar
2 tbsp light corn syrup
Flaky salt (optional)
Coat an 8×8-inch baking pan with 1 tablespoon unsalted butter and line the buttered pan with a parchment paper sling that hangs over two sides of the pan by 2 inches.
Place all ingredients (except salt) in a large heavy-bottomed saucepan and stir to combine. Attach a candy thermometer to the side of the pan.
Cook without stirring over medium-high heat until the mixture reaches 110C or the soft ball stage, 30 to 35 minutes.
Immediately remove the pan from the heat and set aside to cool to 55C (do not stir), 25 to 35 minutes. Once cooled, remove the thermometer and stir with a wooden spoon just until the syrup loses its shine, thickens, and lightens in color, about 10 minutes.
Transfer the fudge mixture to the parchment-lined pan. Do not scrape the sides of the pan clean. Spread into an even layer, sprinkle with flaky salt, if desired, and cool to room temperature, 3 to 4 hours. Cut into 25 squares
