Step 1

Preheat oven to 350°. Line a 9x5” loaf pan with parchment paper, leaving a generous overhang on long sides; set aside.

Step 2

Toast pecans on a rimmed baking sheet, tossing occasionally, until fragrant and slightly darkened in color, 8–10 minutes. Let cool, then coarsely chop.

Step 3

Heat sugar, buttermilk, butter, honey, and kosher salt in a medium saucepan over medium-high heat, stirring occasionally, until butter and sugar are melted, about 3 minutes. Fit saucepan with thermometer, bring mixture to a simmer and cook, stirring occasionally, until thermometer registers 238° (mixture will be pale golden and smell faintly of toffee), 6–8 minutes.

Step 4

Immediately pour mixture into a medium bowl and, using an electric mixer on medium-high speed, beat until cool and thickened (it will be stiff and matte), 5–8 minutes. Fold in pecans. Scrape fudge into prepared pan; smooth top and sprinkle with sea salt. Let sit at least 1 hour before cutting into pieces.

Step 5

DO AHEAD: Fudge can be made 1 week ahead. Store tightly wrapped at room temperature.