Building your cake
No matter whether you plan to pipe designs in buttercream, or smooth fondant or marzipan over the cake, starting with a well-built base makes any cake look more even and helps ensure that the cake holds together well. Click through this slideshow for foundational tips and tricks.
There's a lot of tools needed for cake assembly, and the whole thing goes a lot better when you're organized. Begin by gathering what you'll need: soaker and pastry brush, damp and dry towels, cardboard round, scissors, dowels, offset spatulas, and piping bag and decorating tips, turntable (if you have one), and frosting, whipped to the right consistency.
Apply the soaker
Place the first layer on the cardboard round and apply the soaker. "Soaker" is the term bakers use to describe a solution of water, sugar, and flavoring/liquor that they use to moisten cake layers and give them extra flavor. Apply the soaker to each layer as you build the cake, using a pastry brush.
Apply the first layer of filling
Pipe a circle of the buttercream that you plan to use on the outside of the cake around the perimeter. This will hold the filling inside and keep it from leaking out onto the outside of the cake. Then, make inner concentric circles of whatever filling you choose. I've used the same buttercream in the photo, but you may also use ganache, curd, or jam. Piping the filling first helps ensure that the layers all have approximately the same amount.
Distribute the filling
Use an offset spatula or knife to spread out the frosting into one flat, smooth layer.
Cover with the next layer
Once the first layer of filling is smooth, cover it with the next layer. (Note that in the photo this layer of cake has a huge tear in it; it's very common for bakers to create layers by piecing together pieces of cake. When assembled correctly, no one will notice in the finished product).
Repeat the process
Once the second layer is in place, repeat the process: apply soaker, pipe outer circle of buttercream, pipe filling, smooth, and cover. Repeat again for any additional layers.
Distribute the icing for the crumb coat
Once the layers are stacked, pipe icing onto the top and sides of the cake. The frosting will be spread in two rounds, once for a crumb coat, which is a very thin layer of frosting that is applied to seal the cake and prevent crumbs from getting into the final layer, which is applied on top of the chilled crumb coat.
Apply the crumb coat
Begin by spreading the icing across the top in the thinnest layer possible. Smooth any excess down over the sides of the cake.
Finish the crumb coat
Then, spread the crumb coat in the thinnest layer possible around the sides of the cake, filling in any gaps between layers with frosting. It's fine if you can see through the crumb coat; the most important thing to aim for is a smooth flat top and sides.
Mind the crumbs
While applying the crumb coat, scrape the spatula down on a separate container, away from the one holding your clean frosting, to avoid tainting it with crumbs.
Ready to chill
Once the crumb coat is complete, you're ready to chill the cake for 20 minutes, or, if working with a larger cake, you can insert the supporting dowels at this point, before putting it in the fridge.
This step is not always necessary, depending on the size of the cake, but it's a great trick to know, especially if you are filling the cake with pastry cream or a loose curd, which might cause the layers to slide. If the cake needs to travel I'll do this as a precautionary measure. Insert five wooden skewers or drinking straws all the way through the cake (if the cake is much larger, you can do a second, concentric placement, closer to the edge of the cake).
Pull the dowel up out of the cake just a bit and cut where the dowel met cake. Then push the top of the dowel bak into the cake. Do not worry about how this looks, it will be covered by the second coat of icing. If you choose to use dowels, it is very important that the person serving the cake is aware that they should use caution when cutting and serving the cake.
Apply the final layer of icing
Once the crumb coat has chilled, the cake is ready for a heavier coat of icing. To apply this coat, pipe a good amount of frosting on the top of the cake, and smooth it evenly over the top with an offset spatula. Smooth excess over the sides of the cake. Add additional frosting to the sides until the entire cake is smooth and covered.
A blank canvas
Once the cake is covered with a smooth layer of icing, it is ready to be decorated as you choose, either by piping additional patterns of icing, adding decorative beads or sugars, or smoothing over with rolled fondant.
For some ideas or help with piping techniques, don't miss last week's slideshow, Piping 101.