Preheat the oven to 180°C. Line the bases of 2 x 20 cm cake tins with bake paper and grease the sides with butter.
Cream the butter and sugar together until light and fluffy.
Add the egg and vanilla extract and beat well.
In a separate bowl, sift together the cake flour, salt and baking powder.
Add the flour mixture to creamed mixture, alternating with the pureed strawberries.
Divide the batter between the 2 cake tins and bake for 25-30 minutes, or until a skewer comes out clean.
Allow the cakes to cool slightly in their tins before turning out onto a tray to cool completely.