Add 2 tablespoons of the butter to a medium skillet over medium heat. When melted and foamy, add the pecans. Cook, stirring often, for 4–6 minutes until the nuts smell toasty and a few look slightly darker. Watch closely so they don’t burn, then remove from the heat and let cool.
1 cup pecan halves or pieces, 6 tablespoons unsalted butter
Line an 8×8-inch baking pan with parchment paper, leaving an overhang on two sides to lift the fudge out later. Lightly butter the parchment or spray with nonstick spray.
In a medium heavy-bottomed saucepan, combine the remaining 4 tablespoons butter, brown sugar, granulated sugar, salt, heavy cream, and evaporated milk. Stir over medium heat until the butter melts and the mixture is uniform.
6 tablespoons unsalted butter, 1 cup light brown sugar, 1 cup granulated sugar, 1/2 teaspoon fine sea salt, 3/4 cup heavy cream, 1/2 cup evaporated milk
Bring the mixture to a gentle boil over medium heat, stirring often. Once bubbling across the surface, cook for 5–7 minutes, stirring frequently, until slightly thickened, smooth, and glossy. If using a thermometer, aim for 234–238°F (soft-ball stage).
Remove the pan from the heat and let the mixture sit for about 5 minutes. Stir in the vanilla extract.
2 teaspoons pure vanilla extract
Transfer the hot mixture to a large heat-safe bowl. Gradually add the sifted powdered sugar, about 1/2 cup at a time, beating well with a wooden spoon or a hand mixer on low. Continue until the mixture thickens, loses some of its gloss, and holds soft mounds, pulling away from the sides of the bowl.
2 1/2 cups powdered sugar
Gently fold the cooled toasted pecans into the fudge mixture until evenly distributed. If there is a little melted butter left in the skillet, you can drizzle some of it in for extra flavor.
1 cup pecan halves or pieces
Scrape the fudge into the prepared 8×8-inch pan. Use an offset spatula or the back of a buttered spoon to spread it into an even layer. If desired, press a few extra pecan halves on top for decoration.
additional pecan halves
Let the fudge cool at room temperature for 30–45 minutes, then transfer to the refrigerator for 1–2 hours, until firm but still slightly yielding when pressed.
Use the parchment overhang to lift the slab of fudge out of the pan and onto a cutting board. With a sharp knife, cut into 1–1 1/2 inch squares, wiping the knife between cuts for clean edges. Serve or package for gifting.