Pistachio-Cherry Sandwiches

INGREDIENTS

• 1 large egg yolk
• 1/2 cup sugar
• 1 cup blanched and peeled pistachios (about 4 ounces)
• 1 teaspoon vanilla extract
• 2 sticks unsalted butter, cut into small pieces, softened
• 1 3/4 cups all-purpose flour
• About 1/2 cup sour cherry preserves, for filling
• 2 tablespoons honey