Preheat your oven to 350 degrees F. Line a cupcake pan with 12 cupcake liners.
Cream together the softened butter and granulated sugar until fluffy. Then add the egg whites, vanilla, and peppermint extract, mixing until smooth.
Sift together the cake flour, baking powder, baking soda, and salt. Alternate adding the dry ingredients and buttermilk to the butter mixture, mixing until combined.
Divide the batter evenly among the cupcake liners and bake for 17-19 minutes.
For the ganache, melt the white chocolate, peppermint chips, and heavy cream together. Let it cool until thickened.
For the buttercream, beat the softened butter, salt, and melted white chocolate until fluffy. Gradually add the powdered sugar and peppermint extract, mixing until light and fluffy.
Once the cupcakes are cooled, remove the centers and fill with the peppermint ganache. Frost with the buttercream and sprinkle with crushed candy canes.
Enjoy these festive treats, and remember, they're best enjoyed fresh within three days!