Preheat the oven to 350 degrees F. Add parchment liners to a cupcake pan.

In the bowl of a stand mixer fitted with the paddle attachment, combine the flour, sugar, baking powder, and salt.

Cut up the butter into small cubes and add to the dry ingredients. Mix on low speed until it resembles wet sand.

Add the oil, milk, vanilla, and mix until just combined.

In a separate bowl, whip the egg whites to medium peaks. Gently fold them into the batter with a rubber spatula until just combined.

Fill the cupcake liners about ⅔ of the way full.

Bake the cupcakes for 16-18 minutes or until a toothpick inserted comes out clean.

Cool completely before decorating.

In a small heat-proof bowl, add the white chocolate and place it over a pot of simmering water. Stir often until fully melted. Remove the bowl from heat and set aside.

Place the egg yolks and 12g (1 tbsp) of granulated sugar in a medium bowl or a bowl of a stand mixer fitted with a whisk attachment. Whisk on high speed until thick and foamy (about 3 minutes) while you heat the sugar and water.

Heat the remaining 50g (¼ cup) of granulated sugar and water in a small saucepan over low heat, stirring constantly until the sugar dissolves. Increase the heat to medium and bring to a boil, or until it reaches 240 degrees F.

While the egg yolks are whisking on medium speed, slowly add the sugar syrup into the bowl. Continue mixing until the mixture has cooled down.

Add the butter to the mixture a few cubes at a time, allowing them to fully incorporate before adding more.

Lastly, add the cooled melted white chocolate and vanilla. Continue mixing on low speed until the buttercream is completely smooth.

With a small (about 1") round cookie cutter, remove the centers of the cupcakes, pressing about ⅔ of the way into them. Cut the very top of the centers off and reserve them.

Fill the cupcakes with raspberry preserves and place the top of the centers back on.

Transfer the buttercream to a piping bag with a medium star piping tip.

Decorate each cupcake as desired.