To make blueberry filling:
In a medium saucepan, whisk together the sugar, cornstarch and salt. Stir in water, lemon juice and blueberries. Bring to a boil over medium-high heat, stirring frequently, until mixture begins to thicken. Cook and stir for 2–3 minutes more. Remove from heat and stir in vanilla. Let cool completely.
To make buttercream:
Place flour and sugar in saucepan and whisk to combine. Add milk and cook over medium heat, stirring constantly to boiling. Continue to cook for 45 seconds. Remove from heat, pour into a bowl and cover with plastic wrap directly onto buttercream base and place in refrigerator until cold (overnight is best).
Place butter in bowl of stand mixer and whip until fluffy and lighter in color. Add spoonfuls of Buttercream base, thoroughly incorporating between additions. Add pinch of salt and vanilla and mix for another minute until combined. Set aside in a cool place until ready to frost.
To make lemon cake:
Preheat oven to 350 degrees. Grease and flour 2” high cake pan. In a mixer, cream together butter and sugar until fluffy and lighter in color. Add eggs one at a time, mixing well. Add in vanilla and lemon zest. In a separate bowl, mix together flour and baking powder. To the butter mix, add ⅓ of the flour mix, then ½ of the fresh lemon juice, then the ⅓ of the flour mix, then ½ of the milk. Repeat until all combined.
Pour cake into prepared pan and bake for 35–40 minutes or until a toothpick comes out clean. Let the cake cool for about 10 minutes in the pan, then turn the cake out to cool completely.
While cake is cooling, combine juice from ½ a lemon and 2 Tbsp Sugar. Once completely cooled, slice cake horizontally into thirds.
On a platter, place first layer of cake, and brush cut side with lemon drizzle. Spread layer of icing, topping with Blueberry filling and sprinkle with fresh berries. Add second layer and continue with icing, blueberry topping and berries. Top with 3rd cake layer and top with remaining frosting and fresh berries.
Recipe courtesy of Jackie Collier, Retail Operations Project Manager at Simon Pearce