Steps for the Pinata Vanilla Cupcakes:

• First, it’s important that all ingredients are at room temperature (both for the cupcakes and the frosting).

  Preheat the oven to 350°F. 

  Line a 12-cup muffin tray with liners. 

  Set aside.

  

• Sour cream (or crème fraîche or sour cream) can easily be found in well-stocked supermarkets or organic stores. However, it’s very easy to make at home: in a bowl, whisk 250 g of fresh liquid cream with 70 g of plain whole yogurt (I use Total Fage at 5%); if desired, you can add a few drops of lemon and let the mixture rest at room temperature for 24 hours, covered with a towel.

  After this time, store in the fridge for up to 3 days.

• Prepare the cupcakes: Mix together in a bowl the cake flour, baking powder, baking soda, and salt, and set aside.

• Using a stand mixer with a paddle attachment (or electric whisks), beat the butter (softened to room temperature) at high speed until smooth and creamy (about 1 minute). 

  Next, add the sugar and beat at high speed for 2 minutes, until well combined and creamy. 

  Add the egg whites (at room temperature) and vanilla. 

  Beat at medium-high speed until well combined, then mix in the 120 g of sour cream.

  With the mixer on low speed, add the dry ingredients until well incorporated. 

  Finally, with the mixer still on low, pour in the milk gradually until the mixture is smooth. 

  Do not overmix.

  

• Spoon the batter into the liners – filling them only 2/3 full.

  Bake for 19-22 minutes, or until a toothpick inserted in the center comes out clean.

  

• Let the cupcakes cool in the pan for 10 minutes, then remove them to cool completely before filling.

• Using a stand mixer (or electric whisks), beat the butter at medium speed until creamy (about 2 minutes). 

  Add 4 cups of powdered sugar, the milk (or cream), salt, and vanilla extract with the mixer on low speed. 

  Increase to high speed and beat for another 3 full minutes. 

  Add more powdered sugar if the frosting is too thin or another tablespoon of milk (or cream) if the frosting is too thick. 

  The frosting can be made 1 day in advance, covered, and stored in the refrigerator until ready to use.

• To fill the Vanilla Cupcakes:

  Using a sharp knife (or a metal cylinder, as shown in the photo with the red arrow), cut a circle in the center of the cupcake to create a small deep pocket (BUT do not remove the bottom of the cupcake). 

  Set aside the cut cylinder.

  Place about 1 heaped teaspoon of sprinkles inside the cupcake. 

  

• See the photos to understand how the cupcakes should be filled. 

  Repeat the same process with all the cupcakes.

  

• Once all cupcakes (fully cooled) are filled with colorful sprinkles, cover them with the cut cylinder (as in the photo above) and top with the vanilla frosting, using a piping bag with a star tip. Of course, you can choose not to fill all the cupcakes with sprinkles, to increase the surprise effect.

  

• The cupcakes can be made 1 day in advance, covered, and stored at room temperature. 

  Leftover filled cupcakes (although there won’t be any leftovers!!) can be stored well covered and tightly sealed in the refrigerator for 3 days. 

  Unfilled cupcakes can be frozen for up to 2-3 months. When ready to use, thaw overnight in the refrigerator, then proceed to fill with sprinkles and frosting as explained above.