Use minimal ingredients – just buttercream and jelly – with a super easy technique to create a colourful, shiny design that looks like stained glass but tastes wonderful, too! If you prefer to watch a video of this tutorial, scroll to the bottom of the page.
Before you frost your cake you’ll need to prepare your jelly. Mix 5 little packets of unflavoured gelatin, which is about 35 grams, with 1/2 a cup of water. This makes enough jelly for a tall 4″ or 6″ cake, or a short 8″ cake, but you can scale the recipe up or down depending on the size of your cake.
Leave the gelatin mixture for 3 or 4 minutes to bloom, which makes the gelatin smooth and strong, and meanwhile heat 1 cup of water and 1/2 a cup of granulated sugar over a medium heat until the sugar dissolves and the mixture starts to boil.
Take the pan off the heat and add the gelatin, stirring until it dissolves. Lift out any hard chunks of gelatin that are floating around and try to skim off the foam around the sides of the pan, and this will make the jelly more clear and bright. You can pour it through a sieve to catch any hard chunks of gelatin if you don’t want to scoop them out one by one.
Divide the jelly into a few bowls, however many colours you want to use. I’m going to use gel colours: yellow, orange and red for autumn leaves, brown for a tree trunk and branches, and blue for the sky. Add small amounts of gel colours to each bowl to tint the jelly.
If you want light shades, dip a toothpick into the bottle of colour to get just a tiny bit on the toothpick instead of a full drop. This is also useful when mixing colours, for example mixing a drop of orange with a tiny bit of red on a toothpick to create a darker shade of orange.
The jelly might start to set as you’re colouring the bowls and if that happens, you can still mix in the colour now and then put the bowl in the microwave for 15 seconds at a time to gently reheat the jelly to make it liquid again. If you overheat the jelly you’ll damage the gelatin and it won’t set properly.
As you’re colouring your jelly, keep in mind what you’re going to use that colour for, and how much of the cake it will be covering. I’m using blue for the sky on the sides and top of the cake so I need more blue than any other colour, so I’m using the biggest bowl for this.
Once you’ve made your colours, line a tray or baking tray with parchment paper and pour the jelly on! It’s fine if they run into each other, and if you pour similar colours next to each other you might really like using the pieces of jelly where the colours blend into each other.
Leave the jelly for about an hour to set or you can put it in the fridge for 30 minutes and then peel sections off the parchment and cut them into little shapes.
You can cut them with a pair of scissors, cutting at different angles to cut differently shapes triangles and other random shapes. They might attach to each other, to the scissor blades, or to your fingers a little bit, but they’re not sticky so it’s easy to pull them apart and place back on the parchment.
You can use a knife instead to cut the jelly, scoring random lines and then pulling the pieces of jelly apart. You can assemble and crumb coat your cake before you do this but it’s important to have all of your jelly pieces ready before you frost your cake with the final coat of frosting and I’ll show you why in a moment.
I’m using my 4 Minute Buttercream to frost my cake but this will work with meringue buttercream, whipped cream or ganache as well. Plain white frosting is best because any colours will show through your jelly pieces, tinting them and changing the colours.
The frosting is going to be almost completely covered with jelly but you still need it to be nice and smooth, with straight sides and nice sharp edges at the top. I have a tutorial on how to get perfectly smooth frosting on cakes in case you’re struggling with that!
As soon as you’ve frosted your cake, start creating your stained glass design with the jelly pieces. Press each one gently into the frosting and because you’ve just frosted the cake, the frosting will still be soft and sticky so the jelly pieces will attach to it easily. Don’t worry if you nudge the frosting with a finger and cause a little dent because you can place a piece of jelly over the top to cover it up.
Leave a little gap between each piece of jelly and when you have a space between pieces of jelly, look for another piece that has a similar shape to that space so that it fills its much of the space as possible while still leaving a thin gap between that piece and the pieces surrounding it. You can trim pieces of jelly to fit into small spaces if you need to.
I like to build the basic shape first, so the tree trunk and branches for this design, and then fill in the rest of the design starting with the narrowest areas because you need the smallest pieces of jelly for that, and sometimes very particular shapes like a tiny triangle or a long thin piece.
This is my favourite kind of technique because you can be creative without needing to be perfectly precise – you don’t need to measure distances between the pieces of jelly and if one piece doesn’t quite fit, you can nudge the pieces around it to create a bit more space and since the frosting is still soft you can move the pieces slightly.
You have to work quite quickly to place all of the pieces of jelly before the frosting sets, especially if your cake is cold because then your frosting will set even faster. If it does set and the jelly isn’t sticking anymore, chill the cake to set the frosting so it’s firm and then spread a thin layer over the remaining part of the cake with no jelly on it and then press more jelly pieces onto that area. Don’t forget the top of the cake, unless you want to leave it blank.
In real time, the decorating part of this cake took me 34 minutes, to place all of the jelly pieces to create the design. How do you store a jelly cake? If you put it in the fridge without covering it up, the jelly will dry out and get hard and peel off the frosting. Store the cake in an airtight container in the fridge until 2 – 4 hours before you serve it.
I’m excited for you to try this stained glass jelly cake technique so please tag @britishgirlbakes in your photos on instagram so I can see them!