Mix together the flours and yeast. Add the warm water, whisk thoroughly and keep aside.
Cream together the peanut butter, banana and sugar. Add the milk, salt and egg and blend well.
Add the flour mixture, a cup, at a time, and mix in.
Turn the dough onto a floured board and knead for about 10 minutes. Use more flour to keep it from sticking-a tablespoon at a time. Knead till the dough is smooth and supple.
Place the ball of dough in an oiled bowl and cover with an oiled plastic wrap. Leave aside till doubled in volume.
Punch down the dough , knead for a couple of minutes and shape into a ball. Transfer the ball to an oiled baking tray and pat out to about 8-8and 1/2 inches in diameter. With a sharp knife, make three parallel cuts. Cover loosely with an oiled plastic wrap and leave to rise again till doubled in volume.
Pre heat the oven at 176 deg C.
Dust the dough lightly with flour and bake in the centre of the pre heated oven for approximately 15 minutes or till the top browns. Cover with foil and bake for another 30-35 minutes.
Cool in the tray for a couple of minutes and transfer to a rack to cool completely before slicing.