Lemon-Pistachio Wreaths

Ingredients

• all-purpose flour

  plus more for work surface
  1 cup
• plus 1 tablespoon cornstarch
  3/4 cup
• baking powder
  1 teaspoon
• salt
  1/4 teaspoon
• (1 stick) unsalted butter

  softened
  1/2 cup
• plus 1 tablespoon granulated sugar
  1/2 cup
• egg yolks

  room temperature
  2 large
• finely grated lemon zest

  plus 2 tablespoons fresh lemon juice
  5 teaspoons
• pure vanilla extract
  1 teaspoon
• confectioners' sugar
  1 3/4 cups
• shelled unsalted pistachios

  toasted and coarsely chopped
  1 1/2 cups