Step 1

Grab a large stainless steel pot, weigh it and write the weight down.

Step 2

Blend the strawberries until smooth, transfer to the pot and weigh again - write the weight down.

Step 3

Set the pot on a low-medium flame and bring to a gentle simmer. Allow to simmer for about 45 minutes, keeping an eye on the pot as it likes to boil over and stirring regularly.

Step 4

Stop simmering when the puree reduced to a third. My blended strawberries weighed 900 g / 32 oz and after reduction the weight was 300 g / 10.5 oz. Reduced puree should be thick, paste-like.

Step 5

Divide the reduced puree into two equal portions, refrigerate one half for the icing and keep the other half at room temperature.

Step 6

Grease a 22 cm x 33 cm (9 inch x 13 inch) baking tray, place two wide (and long enough to stick out of the tin) strips of baking paper down first, then line the bottom with a rectangle of baking paper.

Step 7

Preheat your oven to 175° C / 345° F (or 155° C / 310° F on a fan setting).

Step 8

Combine all of the wet ingredients in a large mixing bowl, add reduced strawberry puree and mix well.

Step 9

Combine dry ingredients in another bowl.

Step 10

Place a fine sieve over the bowl with wet ingredients and gradually sift dry ingredients through.

Step 11

Incorporate dry ingredients into the wet ones by making small circles with a spatula in the middle of your mixing bowl first (to minimise lumps). Mix gently but thoroughly until no dry pockets remain (a few lumps is okay). Transfer to the baking tin.

Step 12

Bake for about 35-40 minutes - until the edges pull away from the side of the tin and toothpick inserted in the middle comes out clean. Let it cool a little then using baking paper strips, carefully remove out of the tin and place on a baking rack until cool.

Step 13

Place softened vegan butter in a large mixing bowl and whisk until pale and fluffy - about 3 minutes.

Step 14

Gradually whisk three quarters of the icing sugar.

Step 15

Add cold strawberry puree, tablespoon by tablespoon whisking well after each addition and finally the rest of icing sugar to stiffen.

Step 16

Store in the fridge (or freeze) until ready to use. Bring to room temperature first, before whipping again.

Step 17

If using fresh strawberries to decorate, cut them and blot them on a piece of paper towel first and do not decorate the cake until just before serving - moisture from the strawberries will make the icing weep and look less appetising.