Preheat oven to 325°F (160°C). Line a baking sheet with parchment.

Cream butter and powdered sugar until light, then mix in salt and vanilla.

Stir in wasabi paste until evenly blended; taste a tiny bit to check heat.

Fold in flour until dough just comes together, then stir in white chocolate.

Press dough into a 9x4-inch log or an even disc about 1-inch thick.

Chill 20–30 minutes until firm. Slice 1/2-inch rounds and place 1 inch apart.

Bake 14–18 minutes until edges are set and pale golden. Cool on a rack.