Preheat your oven to 350°F (175°C) and line a cupcake tin with paper liners.

In a large mixing bowl, cream the softened butter and sugar until fluffy. Add the eggs one at a time, incorporating each fully before adding the next. Stir in the vanilla extract.

In another bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add this mixture to the wet ingredients, alternating with the milk, starting and ending with the dry mix. Mix until just combined.

Distribute the batter evenly into the lined cupcake tin, filling each liner about 2/3 full. Bake in the preheated oven for about 20-25 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool completely.

In a saucepan, heat the heavy cream over medium heat until just simmering (not boiling).

In a bowl, whisk together the egg, sugar, vanilla extract, and smoked sea salt until well combined. Gradually add the warm cream to the egg mixture to temper it, stirring constantly.

Once the cupcakes have cooled, cut out a small cone from the center of each cupcake.

Pour the custard mixture over the top, allowing it to fill the cones.

Sprinkle a thin layer of granulated sugar over the custard and use a kitchen torch to caramelize the sugar until golden brown and crispy.

Allow the cupcakes to cool completely before serving.