Vanilla Cream and Glaze

Pour milk into a medium saucepan; scrape in vanilla beans and add pod. Heat over medium heat until steaming. Remove vanilla pod; discard. Meanwhile, whisk egg yolks, sugar, cornstarch, and salt in a medium bowl. Whisking constantly, gradually add milk. Return to saucepan and cook over medium-low heat, whisking constantly, until thickened and whisk leaves a trail, about 2 minutes. Remove from heat and whisk in butter until melted and mixture is smooth. Transfer to another medium bowl; press plastic wrap directly onto surface of pastry cream. Chill until set, at least 2 hours or up to 4 days. Whisk powdered sugar and 1 tablespoon water in a small bowl until smooth. Dip 1 side of warm sufganiyot in glaze; fill with vanilla cream.