Line the bottom of a 15 cm (6") round tin with a circle of baking paper and grease the sides so that the cake doesn't stick when you try to turn it out.
Cream the butter and sugar together until light and fluffy.
Beat in the eggs, one by one.
Sieve in the flour and baking powder and stir to combine. Then add the milk and stir until everything is just mixed.
Scrape into the prepared tin and bake at 180℃ (350℉, Gas 4) for 30 minutes. (I baked mine in my air fryer at 160℃ (320℉, Gas 3)).
The top should be firm to the touch when done and an inserted skewer should come out clean.
Leave in the tin to cool for ten minutes or so, then turn out onto a wire rack to cool completely.
Once cooled, cut the cake in half horizontally. A serrated knife is good for this.
Spread the jam over the bottom half.
Spread the cream over the jam..
Finally, place the top half gently on top of the cream
Dust with icing sugar, if desired.
If doubling the recipe, bake two separate sponges in 20 cm (8") round tins for about 20 minutes, then sandwich with the jam and cream. Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.