Mix 1/4 cup sugar and all the cornstarch in a medium bowl until smooth. Add egg yolks and mix until a paste is formed. Stir in 1/2 cup coconut milk. Combine remaining coconut milk, milk, sugar and vanilla bean seeds in a sauce pan and bring to a boil. Pour hot mixture over egg mixture in bowl, whisking constantly.
Pour back into saucepan. Cook over moderate heat, stirring constantly, until smooth and thick. Remove from heat and stir an additional minute. Transfer to a bowl. Cover with buttered parchment or plastic wrap touching top of cream to avoid skin formation. Chill a minimum of 2 hours or as long as 2 days.Servings: 2 1/2 cups