Beat butter and sugar together with an electric mixer on medium speed, and then add butter extract. Gradually add flour on low speed until just combined.
Roll out dough on a well floured surface to 1/4 inch thick.
Cut out circles of dough and place on a Silpat lined baking sheet.
Bake for 12-15 minutes, watching for the edges of the cookies to start to brown.
Cool cookies on a cooking rack.
Melt wafters according to directions on the package.
Spoon about 1 teaspoon of melted white chocolate onto the top of each cookie spreading it to the edge.
Sprinkle chopped pistachios while the white chocolate is still melty. Allow the white chocolate to set at room temperature before stacking cookies to store.