Confetti Cake:

1. Heat oven to 350°F. Grease and line the bottom of a 9" round cake pan with a circle of parchment paper; set aside.
2. In a large bowl, combine cake mix, oil, and water. Using a handheld mixer, beat on low for 30 seconds. Increase speed to high and beat for another 30 seconds. Fold in rainbow jimmies.
3. Pour batter into prepared pan, smoothing the top with an offset spatula or the back of a spoon.
4. Bake 18–23 minutes. Cake is done when top is lightly golden and edges are set. Also, a wooden pick inserted in the centre will come out clean with only a few fluffy crumbs attached.
5. Allow cake to cool for 15 minutes before removing from pan and transferring to a wire rack. Let cake cool completely.

Confetti Buttercream:

1. Once cake is cool, let’s make some frosting! In the bowl of a stand mixer fitted with paddle attachment, cream butter and salt on medium speed until fluffy and smooth.
2. Sift in a third of confectioners’ sugar (76g), then mix on low until fully incorporated. Scrape down bowl. Repeat two more times with rest of confectioners’ sugar.
3. Mix in sour cream and vanilla, beating until buttercream is your preferred consistency. Fold in rainbow jimmies.
4. Place cake on cake stand or serving platter. Spread frosting on top with an offset spatula. Decorate with additional sprinkles because you can never have too many sprinkles!