Step 1

Line an 8x8-in. pan with parchment paper; set aside.

Step 2

In a medium pot, combine butter, sugars, whipping cream and salt. Stir constantly until it becomes a rapid boil. Monitor temp (without stirring) until thermometer reads 234 degrees F.

Step 3

Remove from heat and add vanilla (without stirring).

Step 4

Cool mixture to about 110 degrees (may take up to 30 minutes). Beat with spoon until fudge mixture starts to thicken. Slowly stir in powdered sugar until smooth. Add nuts and continue stirring until fudge is thick and loses sheen.

Step 5

Spread into prepared pan. Pat off excess butter on top if necessary and refrigerate for at least 1 hour.

Step 6

Using parchment paper, lift fudge out of pan, and cut fudge into squares. Store between layers of waxed paper in an airtight container.