*Before you start, make sure all your ingredients are at room temperature and the butter is soft.
- 225g (1 cup) unsalted butter, softened, plus extra for greasing
- 225g (1 ¾ cup) self-raising flour (or same amount plain (all-purpose flour + 3 teaspoons baking powder)
- 4 large eggs, at room temperature
- 225g (1 ¼ cup) caster (superfine) sugar
- 1 teaspoon vanilla bean paste or extract
- 2-4 tablespoons milk
- Buttercream filling
- 125g (8 ½ tablespoons) unsalted butter, softened
- 125g (1 cup) icing sugar, plus extra for dusting
- ½ tablespoon milk
- ½ teaspoon vanilla bean paste or extract
- 130g raspberry jam, stirred to soften
Preheat the oven to 190˚C (375℉) (do not use fan – if you only have a fan setting lower temperature by 10 degrees). Cut 2 circles of baking parchment to fit in the bases of 2 x 20cm 8-inch) round tins; set aside. Grease, the bottom of the pan, flour the sides and line with paper.
Sift the flour into a medium bowl.
In a jug, lightly beat the eggs; set both aside.
Use electric beaters or a stand mixer fitted with the paddle attachment to beat the butter and sugar together, beat on high and beat for 8-10 minutes, scraping down the bowl every now and then, until the mixture is very pale and fluffy. It should be almost mousse-like.
Continue mixing while gradually adding the beaten egg. If the mixture does start to look grainy, add a spoonful of the sifted flour. When all the egg is added, stop beating and tip in the flour.
Carefully fold it in the flour using a rubber spatula, mix lightly until all the flour is incorporated.
Fold in the vanilla and a pinch of fine salt, followed by enough milk to bring the mixture to a ‘dropping consistency’ (it should drop off the spatula easily when tapped).
Divide the mixture evenly between the tins. Use a rubber spatula to spread the mixture to the edges of the tins, then even the surface, making a slight dip in the center of each (the cake will rise more in the middle, so a dip helps achieve a level sponge).
Bake for 18-22 minutes. The cakes are ready when springy to the (gentle) touch and starting to come away from the edges.
Peel away the parchment and leave to cool completely.
Meanwhile, make the filling: put the butter and sugar in a bowl and use electric beaters to beat until fluffy add the milk and vanilla and mix just until incorporated.
Once the sponges are cool, pour just-boiled water into a mug.
Transfer 1 sponge to a serving plate, if you like trim the very top of the cake to even out, or turn the cake upside down so the flat side is facing up).
Pile all the buttercream on top, then use a palette knife to spread it to the edges, dipping the knife in the mug of hot water and drying the knife on a clean towel every so often to allow the buttercream to spread freely.
Spoon over the jam and spread it out to the edge of the sponge.
Put the second sponge on top, the same way up as it cooled. Use a fine sieve to dust with either caster (superfine) sugar or icing (confectioners/powdered) sugar over the top.