In a medium saucepan, combine heavy cream, milk, granulated sugar (6 Tbsp), salt, and the seeds from the vanilla bean along with the pod itself. Heat over medium heat, stirring occasionally until it starts to bubble gently. Be careful not to let it boil too vigorously to prevent curdling.
While the cream is heating, in a mixing bowl, whisk together egg yolks and the remaining granulated sugar (2 Tbsp) until well blended. Add the cornstarch and mix until the texture is smooth and slightly pale.
Once the hot cream mixture is ready, take about half a cup and carefully whisk it into the egg yolk mixture a tablespoon at a time. This is called tempering and prevents the eggs from scrambling.
After tempering, reduce the heat to medium-low and gradually pour the egg mixture back into the saucepan with the remaining cream mixture, whisking constantly. Cook while whisking until the mixture thickens, which should take about 5 minutes. You'll want to let it boil gently for about 30 seconds to cook out the starchy flavor.
Once thickened, immediately strain the custard through a fine mesh sieve into a bowl to remove any lumps. Stir in butter until melted. Cover the surface of the custard with plastic wrap, pressing it directly against the custard to prevent a skin from forming. Let it chill in the refrigerator for at least 2 hours.
Preheat your oven to 350 degrees Fahrenheit. In a mixing bowl, whisk together flour, baking powder, and salt. Set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment, whip together unsalted butter and granulated sugar (the 3/4 cup + 2 Tbsp) until the mixture is pale and fluffy. This should take about 3 to 5 minutes.
Mix in the egg, then add the egg whites and vanilla extract, blending until well combined.
Add half of the flour mixture to the wet ingredients, mixing just until combined. Pour in the whole milk and blend until combined, then add the remaining flour mixture, mixing until just combined. Be careful not to overmix.
Divide the batter among 12 paper-lined muffin cups, filling each about two-thirds full. Bake in the preheated oven for 21 to 24 minutes, or until a toothpick inserted into the center comes out clean. Transfer the cupcakes to a wire rack to cool completely.
To assemble the Creme Brulee Cupcakes, pipe or spread an even layer of the chilled pastry cream over the cooled cupcakes. Sprinkle a layer of granulated sugar over the pastry cream, then use a kitchen torch to caramelize the sugar until it melts and turns golden brown. Allow the topping to cool slightly.
Garnish with whipped cream and a raspberry if desired. Serve immediately for the best experience, though the pastry cream can be made a day ahead, and the cupcakes can be prepared a few hours ahead—just torch the sugar topping just before serving.
