Warm the egg nog in a saucepan until it’s hot but not boiling. Keep it warm over low heat.
Mix together egg yolks, sugar, salt, vanilla, and cornstarch in a big bowl until smooth and light in color. Slowly stir the warm milk into the mixture until it’s well combined. Cook it in a saucepan until it thickens, stirring constantly.
Remove the creamy mixture from heat, stir in the butter, cover it directly with plastic wrap, and put it in the fridge until it’s cold.
For the Sugar Cookies
Preheat the oven to 350F and line baking sheets with parchment paper.
Mix flour, baking powder, and salt in a bowl and set it aside.
Use an electric mixer to beat the butter and sugar until it’s fluffy. Add eggs and vanilla to the butter mixture, beat until it’s light and fluffy. Slowly add and mix in the dry ingredients until a dough forms.
Shape the dough into balls, coat them with sugar, place them on the baking sheets, gently flatten, and bake for 8-10 minutes. Let the cookies cool on the baking sheet before transferring them to a cooling rack.
To Brulee
Put the chilled pastry cream into a piping bag with a small tip (or just spoon from the bowl and smooth with the back of the spoon).
Once the cookies are cooled, pipe or spoon pastry cream on top of each.
Sprinkle sugar on the cream and use a kitchen blow torch to caramelize the sugar. Let the cookies cool a bit after torching before serving.
Notes
This recipe can be multiplied wo make the number of cookies you desire.