Toss apples with self raising flour and sugar in a medium mixing bowl.
Melt butter in a small saucepan on the stovetop or in a small bowl in the microwave, stir in egg. Pour butter and egg into the apple mixture. Mix until combined.
Spoon into a greased and lined slice tin. Bake at 180 C for 35 to 40 minutes or until the top is golden brown and a skewer inserted into the middle comes out clean. Keeps for about 3 days.