Lemon Squares

INGREDIENTS

• 1 tablespoon all-purpose flour
• 1 cup (2 sticks) butter, at room temperature
• 2 cups granulated sugar
• 5 tablespoons fresh lemon juice (from about 2 large lemons)
• 2 tablespoons grated lemon zest
• 2 cups all-purpose flour
• 1/2 cup confectioners' sugar, plus more for sprinkling
• 1/2 teaspoon salt
• 1 teaspoon baking powder
• 4 large eggs