Lightly butter an 8 x 8-inch baking pan and set it aside to be ready for the fudge.

Combine the sugar, heavy cream, butter, and salt in a large saucepan over medium-high heat. Stir constantly with a whisk while heating until small bubbles form around the edges.

Reduce the heat to medium and continue to cook the mixture for 4 minutes, keeping it at a gentle simmer and whisking without pause so it thickens slightly but does not reach a rolling boil.

Take the pan off the heat and wait about 15 seconds for bubbling to subside. Then add the white chocolate chips and stir until they begin to soften and melt into the warm cream base.

Fold in the mini marshmallows and the toasted pecans, stirring until the white chocolate is fully melted and the mixture is uniform. Small bits of marshmallow that remain are fine.

Pour the fudge mixture into the prepared pan, smoothing the top with a spatula. Chill in the refrigerator until it becomes firm, about 1 hour.

Lift the set fudge from the pan onto a cutting board and slice into 1 x 1-inch pieces. Serve and enjoy.

Storage: keep fudge at room temperature in an airtight container for up to 1 week, refrigerate for 2 to 3 weeks, or freeze for longer storage.

Yield: this recipe makes about 1 3/4 pounds (approximately 800 grams) of fudge, roughly 64 one-inch pieces.