Old-fashioned Buttermilk Fudge

Combine buttermilk, granulated sugar, and baking soda in a heavy-bottomed saucepan. Stir until the sugar dissolves and the mixture is well combined.

Heat the mixture over medium heat, stirring occasionally, until it reaches a soft-ball stage (approximately 235–240°F on a candy thermometer).

Remove from heat and stir in the unsalted butter until fully incorporated.

Allow the mixture to cool to approximately 110°F (about 5 minutes), then beat vigorously with a wooden spoon or hand mixer until the fudge thickens and loses its gloss, about 2–3 minutes.

Fold in the chopped pecans until evenly distributed throughout the fudge.

Pour the fudge onto a buttered or parchment-lined 8x8-inch baking pan, spreading it evenly with a spatula.

Allow the fudge to cool completely at room temperature for at least 2 hours, then cut into 1-inch squares and serve.