Instructions

For the Cake:

1. Preheat oven to 350 degree F. Line two muffin tins with cupcake liners.
2. Sift together the flour, baking powder, baking soda, and salt in a medium bowl.
3. In the bowl of an electric stand mixer fitted with a paddle attachment, cream the butter, and sugar on medium speed until light and fluffy, about 3-4 minutes.
4. Add the eggs one at a time, beating well to combine and scraping down the bowl as needed. Add in the vanilla extract and rose water.
5. Reduce speed to low, add a third of the dry ingredients and half of the buttermilk and beat until just combined. Add another third of the flour mixture and the rest of the buttermilk and beat again until combined. Add the rest of the flour mixture and beat until combined. Fold in the white chocolate by hand with a rubber spatula.
6. Divide batter into cupcake liners and bake until golden brown or until a tester comes out clean, about 12-15 minutes.
7. Cool in pan for 2-3 minutes before moving to a cooling rack to cool completely.

For White Chocolate Swiss Meringue Buttercream:

1. Whisk together sugar and egg whites in a heatproof mixing bowl set over (not in) a pan of simmering water. Whisk until warm and sugar is dissolved (mixture should feel completely smooth when rubbed between your fingers), 2 to 3 minutes. Remove from heat.
2. With an electric mixer on medium speed, whisk egg white mixture for 5 minutes. Increase speed to medium-high, and whisk until stiff, glossy peaks form and meringue has cooled (test by the feeling bottom of the bowl), about 6 minutes.
3. Reduce speed to medium. Add butter, one piece at a time, beating well after each addition. Keep beating until the buttercream comes together. It takes a few minutes but keep beating with the electric mixer. Beat in vanilla extract and rose water. Mix in the white chocolate into the buttercream and mix for about a minute to combine.
4. Use immediately to frost cupcakes or store in an airtight container in fridge for up to a week.