1 1/4 cups all-purpose flour, plus more for dusting
1/4 cup sugar
1 teaspoon finely grated lemon zest
1/4 teaspoon salt
1 stick cold unsalted butter, cut into 1/2-inch pieces
1 large egg yolk
Cooking spray
1/2 cup sugar
4 large egg yolks
3 tablespoons cornstarch
Pinch of salt
1 1/2 cups whole milk
2 tablespoons unsalted butter
1 teaspoon vanilla extract
1/2 cup cold heavy cream
1 tablespoon poppy seeds