Sour cream blueberry cake with vanilla mascarpone icing

From First, Cream the Butter and Sugar by Emelia Jackson, Murdoch Press
9 February 2023
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Recipe

A slice of double-layered sour cream blueberry cake with vanilla mascarpone icing sits on a plate, two slices on plates are in the background

Image: Armelle Habib

Understanding why you use an ingredient is crucial to mastering baking and building confidence. The high fat content of sour cream means it adds a lovely richness to cakes, while the acidity adds a tender texture, which is exactly what you’re looking for in a vanilla cake. And because it’s thick, it won’t thin out the batter and affect the way the cake cooks. You can substitute the sour cream with a thick, Greek-style yoghurt.

Makes one 18 cm two-layer cake

WHAT YOU NEED

For the sour cream blueberry cake
200g caster (superfine) sugar
170g unsalted butter, softened
Grated zest of 3 lemons or ½ tsp lemon extract
1 tbsp vanilla bean paste or extract
1½ tsp baking powder
½ tsp bicarbonate of soda (baking soda)
½ tsp salt
3 eggs
120g sour cream
120ml full-cream milk
220g cake flour (see below* or store bought)
200g fresh or frozen blueberries (not thawed)
125g fresh blueberries, to serve
Grated zest of 1 lemon, to serve

Vanilla mascarpone icing
250g chilled mascarpone cheese
200ml chilled thickened (whipping) cream
100g icing (confectioners’) sugar
1 tbsp vanilla bean paste

* Cake flour
Using cake flour makes a huge difference to a cake. It’s a low-protein flour that helps you achieve the most tender, fluffy, and light cakes imaginable. There’s no need to race out and buy cake flour—it’s literally just plain (all-purpose) flour with some cornflour (cornstarch) or potato starch added to reduce the gluten content.
To make your own cake flour
Measure out 430g plain (all-purpose) flour, then add 70g cornflour (cornstarch) or potato starch and sift together.
Adding the cornflour or potato starch reduces the gluten content in the plain flour from 11 per cent to between 7 and 9 per cent. Emelia makes it in a big batch so it’s always ready to go.

WHAT TO DO

Preheat the oven to 160°C. Line two 18cm round cake tins with baking paper.

Using an electric mixer fitted with the paddle attachment, mix the sugar, butter, and lemon zest or lemon extract until light, creamy, and fluffy. Add the vanilla, baking powder, bicarbonate of soda, and salt and mix until thoroughly combined. (Emelia likes to add the raising agents at this point to ensure they are evenly dispersed throughout the cake batter, creating an even rise in the final cake.) Add the eggs, one at a time, and beat until combined.

Whisk the sour cream and milk in a small jug or bowl.

Sift the flour over the egg mixture, then gently fold together until combined. Lightly mix in the sour cream mixture until the batter just comes together.

To prevent all of the blueberries from sinking to the bottom of your cake, first divide a quarter of the batter between the cake tins and smooth the top. Mix the blueberries through the remaining batter and divide it between the tins.

Bake the cakes for 40–45 minutes or until a skewer inserted into the centre of each cake comes out clean. Allow the cakes to cool in the tins for 10 minutes before turning them out onto a wire rack to cool completely.

For the icing, whisk the mascarpone, cream, icing sugar, and vanilla in a bowl until thickened. Be careful not to over-whisk the cream as it can easily split.

Use a serrated to knife to level the tops of the cakes, if needed. Put one of the cakes on a serving plate and spread it with about a third of the icing. Add the second cake and spread the remaining icing all over the top and side. Garnish the cake with the fresh blueberries and lemon zest.