This quick pizza can be made to suit fussy eaters at home. Half of the pizza can have all your favourite toppings, leaving the other half for your fussy eater to fill with all their favourites.
Preheat the oven to 200°C/gas mark 6. Line a baking tray with non-stick baking paper.
Unroll the pastry onto the lined tray. Crumble the blue cheese evenly over the pastry, then scatter the mushrooms and red onion on top, making sure you keep a 3cm border clear around the edge of the pastry. Brush the clear border with the beaten egg.
Bake in the oven for 20 to 25 minutes, until the puff pastry has risen and is golden brown. Cut into slices to serve.