poppy seed lemon cake

INGREDIENTS

• 2/3 cup sugar
• 8 large egg yolks
• 1 large whole egg
• 1 1/2 tablespoons finely grated lemon zest (from 2 lemons)
• 1/2 cup all-purpose flour
• 1/2 cup cornstarch
• Pinch of salt (edited to add this)
• 2 sticks (1/2 pound) unsalted butter, melted and cooled a bit
• 1/2 cup poppy seeds (I got this from one 3-ounce spice bottle)