Tip the bread mix into a large bowl. Add the oil and rub in with your fingertips, then quickly stir in 340ml warm water, until it comes together to a sticky dough. Tip the dough onto a floured surface and knead for 10-15 minutes, until smooth and elastic – it should spring back to the touch.
Grease a large bowl with the extra olive oil. Put the dough in the bowl, cover with cling film and leave in a warm, dry place until it has doubled in size – about 1 hour.
Knock the air out of the dough and knead briefly. Divide the dough into 8 pieces and cover with a clean tea towel. Take one portion at a time and divide into 5 pieces of graduating size. Roll the pieces into balls.
Line a baking tray with baking parchment, then place the balls in a line, in descending size order, so they are just touching each other (bend in a slight ‘c’ shape to form a caterpillar shape). Repeat with the remaining dough pieces.
Brush the caterpillar buns all over with some of the beaten egg, make cuts for mouths, then press on the olive slices for eyes. Leave to rise for a second time – about 30 minutes. Brush all over again with the remaining beaten egg.
While the caterpillars are rising, preheat the oven to 200ºC, fan 180ºC, gas 6. Bake the caterpillars for 30 minutes, until golden and they sound hollow when tapped.