Birthday Cake Petit Fours

Ingredients

• Cake
• 8 ounces (227g) unsalted butter, at room temperature
• 1½ cups (298g) granulated sugar
• 3 large (170g) eggs, at room temperature
• 2 teaspoons pure vanilla extract
• 2¼ cups (271g) all-purpose flour
• ½ teaspoon baking powder
• ¼ teaspoon fine sea salt
• ½ cup (121g) whole milk, at room temperature
• ⅔ cup (142g) rainbow sprinkles
• Filling
• 6 ounces (170g) unsalted butter, at room temperature
• 3 cups (340g) confectioners’ sugar
• 3 tablespoons (43g) heavy cream
• Icing
• 8 cups (907g)confectioners’ sugar
• ½ cup (312g) light corn syrup
• ½ teaspoon pure vanilla extract
• Rainbow sprinkles, as needed for finishing