Make the Pastry Cream:Whisk the egg yolks, sugar and salt in a bowl. Add cornstarch and whisk. Add heavy cream to a pan, once it reaches a simmer, whisk it into the yolk mixture.
Return it to the pan and cook until it’s a thick pudding consistency. Remove from the heat, and whisk in the butter and vanilla extract. Transfer to a bowl, plastic wrap, and refrigerate until set (2 hours minimum)
Make the Cupcakes:
Mix flour, sugar, baking powder & Salt. Add butter; and mix, then eggs. Add milk and vanilla; mix until smooth. Fill muffin cups. Bake about 19-20 minutes at 350 degrees F then let cool for 5 minutes.
Assemble the Cupcakes: Cut a cone out of the top of each cupcake.Fill each with pastry cream and top with a disk of cake. Spread the glaze over top and refrigerate until set.