Mary Berry's Frosted Walnut Layer Cake |  

Mary Berry's Frosted Walnut Layer Cake recipe is featured as the technical challenge in the "First" episode of The Great British Baking Show.
Original Recipe :
www.pbs.org/fo...
www.bbc.co.uk/...
I was so inspired by GBBO that I wanted to try all the technical challenge recipes.
GBBO S06E01 - First - Mary Berry's Frosted Walnut Layer
I made half the original recipe because, during covid pandemic it is not possible to share the bakes with my friends & neighbors.
Ingredients
For the sponges:
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Flour - 112.5 grams/ 4 oz
Baking powder - 1½ teaspoons
Salt - ¼ teaspoon
Walnuts - 50 grams/ 1¾ oz, roasted & finely chopped
Butter - 112.5 grams/ 4 oz, softened
Caster sugar - 112.5 grams/ 4 oz
Eggs - 2 large
For the Caramelized Walnuts:
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Caster sugar - 50 grams/ 1¾ oz
Water - 1 tablespoon
Walnut halves - 5
For the Buttercream:
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Butter - 62.5‬ grams/ 2¼ oz, softened
Vanilla extract - ¼ teaspoon
Milk - 1 tablespoon
Icing sugar - 125 grams/ 4½ oz
For the Boiled Icing:
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Egg white - 1 egg
Caster sugar - 175 grams/ 6 oz
Water - 2 tablespoons
Cream of tartar - ⅛ teaspoon