Line an 8-inch square pan with parchment, leaving an overhang.
Pat chopped cherries completely dry with paper towels; set aside.
Combine white chocolate, condensed milk, and butter in a saucepan over low heat.
Stir constantly until mostly melted and smooth; remove from heat.
Stir in vanilla, almond extract, and salt until glossy.
Fold in cherries and almonds, if using, until just combined.
Scrape mixture into the pan; smooth the top and tap to settle.
Refrigerate until firm, 2 to 3 hours.
Melt extra white chocolate and drizzle over the set fudge, if desired. Cut into squares.