Fill a pastry bag fitted with a large round tip (size 807) with some of the frosting and set aside.
Line a cake stand or plate with a few strips of parchment paper and place 1 layer of cake on top.
Add ⅓ cup of frosting on top of the cake and spread it out evenly with a spatula. Crumb coat the side of the cake with some additional frosting. Pipe a border around the edge of the cake layer using the previously prepared frosting in the pastry bag.
Add ⅓ cup of lemon curd filling within the frosting border and place the cake in the refrigerator to allow the frosting and filling to firm up before adding the second layer of cake on top, about 30 minutes.
Place the second cake layer on top of the refrigerated cake layer, and spread ⅓ cup of frosting on top. Crumb coat the side of the second cake layer and fill in the gap between the two layers with some additional frosting. Refrigerate for another 30 minutes to allow the crumb coat to firm up before finishing decorating the cake.
Once the crumb coat is set, take the cake out of the refrigerator and add a thin layer of frosting on the side and top of the cake. Smooth out the frosting with an offset spatula.
Add the remaining frosting to a pastry bag fitted with a star tip (1M), pipe a border around the edge. Add the remaining lemon curd within the border and spread it out carefully with the back of a spoon.
Refrigerate for 2 hours to let the frosting set before serving.