Cookie Monster Cake (for Decorating Beginners)

Bahan-bahan (12 porsi)

• 2 and 1/2 cups (285g) cake flour (spooned & leveled)
• 2 teaspoons baking powder
• 1/2 teaspoon baking soda
• 1 teaspoon salt
• 3/4 cup (12 Tbsp; 170g) unsalted butter, softened to room temperature
• 1 and 3/4 cups (350g) granulated sugar
• 5 large egg whites, at room temperature
• 1/2 cup (120g) sour cream, at room temperature
• 1 Tablespoon pure vanilla extract (yes, Tbsp!)
• 3/4 cup (180ml) whole milk, at room temperature
• 1 cup (180g) mini chocolate chips
• 1 Tablespoon (7g) cake flour
• 1 and 1/2 cups (340g) unsalted butter, softened to room temperature
• 6 and 1/4 cups (750g) confectioners’ sugar
• 1/3 cup (80ml) whole milk or heavy cream, at room temperature
• 2 teaspoons pure vanilla extract
• 1/8 teaspoon salt
• blue and black gel food coloring
• one 4-ounce white chocolate bar (113g), finely chopped*
• 1/2 teaspoon vegetable oil or coconut oil