In a bowl, dissolve cornstarch in cream with a whisk. Add egg yolks and whole egg. Slowly incorporate into infused milk. Cook over low heat, stirring constantly with a wooden spoon or spatula, taking care to scrape the bottom of the pan, until mixture thickens and coats the back of a spoon. Remove from heat and strain. Cover with plastic wrap directly on cream and let cool in the refrigerator or over an ice water bath. Set aside.