Preheat the oven to 350 degrees F (177 C). Line 12 cupcake tins with paper liners.

Combine flour, baking powder, and salt in a medium bowl. Stir to mix well.

Prepare an electric mixer and set it aside. Create a double boiler by choosing a medium and a small pot, so you can stack the small one into the medium pot. Add water to the medium pot to the height that covers the bottom of the small pot. Bring water to a simmer. Add white chocolate, butter, lemon juice, and milk to the small pot. Dip the bottom of the small pot into the simmering water. Whisk and cook until the ingredients are melted and combined. Remove the small pot from the water and place it on a working surface. Immediately add the granulated sugar into the small pot, and whisk at low speed with an electric mixer until the sugar is fully incorporated.

Add the eggs, one at a time. Whisk to mix well.

Add the vanilla extract. Whisk to mix well.

Gradually add the dry mixture, mix until just incorporated.

Fill the lined cupcake tins with the batter until almost full. Bake for 17 to 20 minutes, until a toothpick inserted into the center comes out clean.

Transfer to a cooling rack to cool down completely. You can make the cupcakes a day ahead and store them in a container at room temperature.

Add chocolate and 1/2 cup heavy cream into a medium-sized bowl. Microwave in 30-second increments, until the chocolate is melted and starts to release the yellow cocoa butter, about 1 minute in total. Whisk until the white chocolate is fully dissolved, 2 to 3 minutes. Seal the bowl with plastic wrap and store it in the fridge until the mixture is chilled, 3 to 4 hours.

When you’re ready to serve, combine the white chocolate mixture with the remaining 1 cup chilled heavy cream in a large tall bowl. Whisk on high speed until stiff peaks just form.

To assemble, spoon some white chocolate cream onto the cupcakes and garnish with berries. Serve with the rest of the frosting on the side.

The cupcakes will hold up at room temperature for a day or two, and in the fridge for 4 to 5 days. Always store the frosted cupcakes in an airtight container in the fridge. Let them rest at room temperature for 20 to 30 minutes before serving, to bring the texture back to life.