• Preheat the oven to 350° F.
  
• Line a muffin pan with cupcake liners.
  
• In a medium bowl, whisk eggs and vanilla.
  
• In a large bowl with an electric mixer, beat together sugars and vegetable oil.
  
• Combine in sourcream.
  
• In a medium bowl, combine flour, cocoa powder, baking powder, baking soda, and salt.
  
• Add egg mixture into the sugar mixture. Mix well with an electric mixer at a low speed.
• Pour half of the dry ingredients into the wet ingredients. Whisk between each addition using a kitchen hand mixer. Add the rest of the dry ingredients.
  
• Spoon cupcake batter with a large (2.4 inch) batter scoop onto the liners.
  
• Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Cool completely on a cooling rack.
  

Chocolate filling

• Transfer store-bought chocolate Bavarian cream into the piping bag. Cut 3/4 inch with scissors from the tip of the bag. If you have more time, then make a homemade chocolate ganache.
• After cupcakes are completely cooled, hole each cupcake with a size 2A metal tip.
  
• Pipe chocolate cream into cupcake holes and cover-up.
  

Vanilla buttercream frosting

• Scoop store-bought buttercream frosting into a large bowl. Beat on medium speed with an electric mixer for 2-3 minutes. If you have more time, then prepare the homemade buttercream frosting.
  
• Transfer 1/3 of buttercream frosting into a piping bag lined with a metal tip.
  
• Add blue food coloring with a toothpick into the rest of the icing. With rubber spatular mix until frosting has even color.
  
• With a small batter scoop (1.6 inch), scoop blue buttercream frosting on top of each cupcake. Spread frosting evenly with a cake spatula or butter knife.
  
• Pipe clouds with a white buttercream frosting. Insert sweet and sour rainbow candy into the clouds.