Preheat the oven to 350°F. Line a 12 cup muffin pan cupcake liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
To the bowl of a stand mixer fitted with a whisk attachment, add the butter and sugar and cream together on medium speed for about 3 minutes or until the butter is pale yellow, scraping down the sides, as needed.
Add the eggs, greek yogurt, oil, milk, and vanilla, and continue mixing until smooth.
Add the flour mixture and beat on medium speed until no more flour streaks remain.
Scoop batter into the prepared muffin pan, filling each cup 3/4 full. Bake for 15 to 17 minutes or until a toothpick inserted in the middle comes out clean. Cool in the pan for a few minutes, then transfer to a wire rack to cool completely.
Make the Buttercream
Add butter to a clean bowl of a stand mixer fitted with a paddle attachment. Beat on medium speed until light in color and increased in volume.
Scrape down the sides and add the powdered sugar. Mix for about 2 minutes until combined, and then add the vanilla, cream, and salt. Continue to mix until smooth and creamy, about another 2-3 minutes.
Transfer the frosting to a piping bag fitted with your desired tip and frost cupcakes. Top with white sparkling sugar and a snowflake for decoration.