Prep the pan: Line an 8x8-inch baking pan with parchment, leaving overhang on two sides for easy lifting. Lightly grease the parchment if needed.

Combine base ingredients: In a medium saucepan, add white chocolate chips, sweetened condensed milk, and butter.

Heat gently: Warm over low heat, stirring constantly with a rubber spatula until smooth. Keep the heat low to avoid scorching or seizing.

Flavor it: Remove from heat and stir in vanilla and a pinch of salt. Mix until glossy and uniform.

Add the sprinkles: Let the mixture cool for 1–2 minutes so it’s warm, not hot. Fold in the sprinkles gently so the colors don’t bleed.

Pour and top: Spread the fudge evenly in the prepared pan. Sprinkle extra jimmies on top and press lightly to set them.

Chill: Refrigerate for 2–3 hours, or until firm enough to slice cleanly.

Slice and serve: Lift the fudge out using the parchment. Cut into small squares with a sharp knife. Wipe the knife between cuts for neat edges.