Hi
The mixing method I use is all in one, I mix by hand using a silicon spatula, I use a fan assisted oven and bake at 160 use two 20cm cake tins as per the recipe book, the pans are non stick.
Victoria sponge is very unusual in that you determine the amount of sugar, flour, and butter based on the weight of the eggs in the shell.
Self rising flour has baking powder in it. You do not need to add anymore. Too much baking powder will simply cause the cake to collapse.
It is not just the recipe that determines the temperature of the oven. The type of pan you are using affects how the batter bakes. A nonstick pan, anodized aluminum, dark metal will bake much hotter than a natural light colored uncoated metal cake pan.
Fan assist oven also bakes hotter as the heat circulation creates more surface to the oven temperature by 15° – 25°.
But since you are already baking at 160°C, I wouldn’t reduce the temperature further. Rather, reduce the amount of batter in the cake tin. Cake batter bakes from the outside inward. If there is too much batter in the tin, the outside edge, bottom, and top
is going to bake much faster than the center.
The best test to determine whether or not a cake is done is by the internal temperature. Using the toothpick test is really ineffective. Bake to an internal temperature of 205°F (96°C) - 210°F (99°C). Do not let the cake reach 212°F (98.8°C). This is the temperature in which water boils. The evaporation results in a much drier cake.
Begin testing for doneness a few minutes before the recipe stated bake time.
The recipe and mixing method you have been using is the Mary berry recipe. This is not a traditional Victoria sponge recipe. Her modern all in one mixing method is fast and easy. But it creates a very thick and heavy batter. That in turn creates a heavy cake.
The addition of extra baking powder is meant to counter the dense texture. But additional baking powder and the high sugar content can undermine
the structure of the cake. Sugar is a tenderizer. So too much baking powder and high sugar content will cause a cake to collapse.
If you decide to use extra baking powder, keep in mind that the standard is 1 teaspoon for up to 140g of flour. So 2 teaspoons of baking powder, it’s enough to rise 280g flour. That is in addition to the baking powder that is already in the flour.
Aside from the mixing method and the additional baking powder, Mary Berry’s recipe other major failing point is her failure to weigh the eggs and her failure to even mention the appropriate size egg to purchase.
Victoria sponge is unique in that the amount of flour, sugar, and butter are all determined by the weight of the eggs in the shell.
In the UK, a large egg must weigh between 63 g – 73 g. The weight of four large eggs is between 252 g – 292g. But Mary Berry’s recipe only had 225 g (8 oz) each of flour, sugar, and butter.
Four larger eggs is 11% - 29% higher than the weight of flour, sugar, and butter.
The weight of a medium egg in the shell in the UK must be between 53 g – 63 g. So four eggs would be between 212g - 252g.
By failing to weigh the eggs, Mary Berry’s recipe never uses the correct amount of flour, sugar, and butter to egg.
To get a better bake in a 20cm cake tin, reduce the amount of batter. Use large eggs. Use three eggs instead of four.
You can also insulate the pans with wet cloth baking strips. See note at end of post.
Three large eggs in the shell should weigh between 189g - 219g.
Use the creaming method to incorporate air into the batter. Creaming is mechanical leavening. It is the traditional mixing method for a Victoria sponge. If you do not own a mixer, whip butter with a fork for a couple of minutes. Then add the sugar in three additions, mixing well after each addition.
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Traditional Victoria Sponge
- Preheat oven to 160°C line
- Lightly grease sides of two 20 cm cake tins
- Line bottom of tins with parchment baking paper
INGREDIENTS
- Weigh three large eggs in the shell.
- Weigh Self-rising Flour equal to the weight of the eggs in the shell
- Weigh Caster Sugar equal to the weight of the eggs in the shell
- Weigh Butter equal to the weight of the eggs in the shell. Let butter warm 20°C.
You don’t want the butter too warm since mixing causes friction heat. Too warm butter will not aerate properly.
CREAMING METHOD
Place sugar and butter in a mixing bowl.
Cream on medium speed for 2 1/2 minutes.
Scrape down the sides and bottom of the bowl.
Continue creaming for approximately 2 minutes more.
Add the egg in three additions.
Scrape down the sides and the bottom of the bowl after each addition.
Sift the flour into the butter mixture. Sifting is important to aerate the flour.
Mix until just combined.
Divide batter between two cake tins
Check temperature after 23 minutes.
Bake to internal temperature 205°F (96°C) - 210°F (99°C).
Do not let the internal temperature reach 212°F (98.8°C).
If your oven temperature is accurate, total bake time should be between 25 minutes and 28 minutes. If you bake to 30 minutes the cake will most likely be dry.
NOTE: if you decide to use additional baking powder sifted it into the flour at least three times to ensure it has been properly distributed.
Wrapping strips of wet cloth around the outside of the baking tins insulates the tin. This allows for the batter to bake more evenly from the outside in. The cake will also bake more level. I use cloth baking strips every time I use a round or square cake tin. With baking strips, my cakes are always perfectly level on top.
They are commercially available through several companies. The brand I use is Wilton. You can also make them yourself.
Just be sure the fabric is not too heavy. And do not over lap the fabric around the pan. Soak the strips in water for about five minutes to fully saturated. Then squeeze out the excess water before wrapping the strip around the cake tin.
http://www.acozykitchen.com/how-to-bake-flat-cake-layers/
Wilton baking strips
https://www.amazon.co.uk/Wilton-Bake-Strip-Steel-6-Piece/dp/B00C1LU8SA
