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

In a medium mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and fine salt until well combined.

Create a well in the center of your dry mixture and add the sour cream, water, oil, egg, and vanilla. Mix until smooth.

Divide the batter among the cupcake liners, filling each about three-quarters full.

Bake for 18-20 minutes, until lightly golden and a toothpick comes out with moist crumbs.

Let the cupcakes cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.

In a mixing bowl, beat the butter, vanilla, and a pinch of salt until creamy. Gradually add powdered sugar and mix in melted white chocolate and raspberry jam.

Melt the white chocolate chips and heavy cream, stirring until smooth to make the ganache.

Remove cupcake centers, fill with raspberry jam, then pipe the buttercream frosting on top.

Drizzle the ganache over each cupcake and garnish with fresh raspberries and chocolate shavings.