How to Make It
Preheat oven to 350°F. Grease and flour 2 (8-inch) round cake pans.
Prepare the Cake: Beat together sugar and butter with an electric mixer on medium speed until light and fluffy. Add eggs, 1 at a time, beating after each addition, stopping to scrape down sides as needed. Beat in vanilla.
Whisk together flour, baking powder, and salt in a medium bowl. Add flour mixture and buttermilk alternately to butter mixture, beginning and ending with flour mixture. Beat at low speed until fully blended after each addition. Divide batter evenly between prepared cake pans.
Bake in preheated oven until a wooden pick inserted in center comes out with moist crumbs, 25 to 30 minutes. Cool in pans 15 minutes, then invert cake layers onto a wire rack until completely cooled, about 1 hour. (For best results, wrap each cake layer in plastic wrap and chill until ready to frost.)
Prepare the Frosting: Beat butter in a stand mixer fitted with the paddle attachment on medium speed until pale and fluffy, about 5 minutes. Scrape down sides and bottom of bowl twice while beating. With mixer running on low speed, gradually add powdered sugar, beating until smooth, about 2 minutes, stopping to scrape down sides of bowl as needed. Beat in vanilla and salt. With mixer running on medium speed, gradually add cream, beating until fluffy and spreadable, about 30 seconds. (For best results, beat frosting by hand with a wooden spoon for about 2 minutes to remove air bubbles.)
Spread frosting between cake layers and on top of cake. Use a bench scraper for smooth sides. Sprinkle candy sprinkles around top edge and around base of cake.