How to Make It
Prepare the Cake: Preheat oven to 350°F. Line bottoms of a 8-inch round cake pan and a 8-inch square cake pan with parchment paper. Grease and flour bottom and sides of pans.
Beat together sugar and butter in the bowl of an electric mixer at medium speed until light and fluffy, 4 to 5 minutes. Whisk together flour, baking powder, and salt in a large bowl. Alternately add flour mixture and half-and-half to butter mixture in 5 additions, beginning and ending with flour mixture. Stir in vanilla; fold in chopped strawberries.
Place egg whites in a large bowl. Using clean dry beaters, beat eggs at medium speed until foamy, 1 minute; increase speed to high, and beat until stiff peaks form, about 2 minutes. Stir 1/4 of egg whites into cake batter; gently fold remaining egg whites into batter. Divide evenly between prepared pans smoothing tops with a spatula. Bake in preheated oven until a wooden pick inserted in the centers comes out clean, 26 to 28 minutes. Cool cake in pans on a wire rack for 10 minutes. Remove cake from pans; cool completely on rack, 30 minutes.
Prepare the Frosting: Stir together gelatin and water in a small microwavable bowl. Let stand 5 minutes. Microwave on HIGH until gelatin melts, 8 to 10 seconds (do not boil).
Beat together cream, powdered sugar, and vanilla in a large bowl with an electric mixer on medium speed until mixture begins to thicken. Gradually add gelatin. Increase speed to high, and beat until stiff peaks form. Place 2 cups of whipped cream into a piping bag fitted with a star tip for decorating the cake.
Cut round cake in half. Place square cake, bottom side up, on a serving plate. Place each half of the round cake, bottom side up, on adjacent sides of square cake to form a heart. Spread about 1/2 cup whipped cream on cut sides of round cake, and then press into square cake to seal. Spread sides and top of cake with remaining whipped cream. Pipe decorative border on bottom and top edges of cake with whipped cream in piping bag. Chill 1 hour.
Garnish the Cake: Melt candy melts according to package directions. Hold a berry by the stem end, and dip three-quarters of it into melted chocolate, making sure to coat berry’s surface and letting excess drip back into bowl. Immediately sprinkle desired garnish onto dipped strawberry. Place on a baking sheet lined with parchment paper. Repeat with remaining strawberries. Chill until chocolate is set, about 30 minutes. Arrange strawberries on cake.