VEGAN WHITE FRYING-PAN PIZZA

2 tbsp olive oil, plus extra to drizzle • ½ x 385g pack butternut squash wedges • ½ red onion, very thinly sliced • Plain flour, for dusting • 220g Northern Dough Co. Original Pizza Dough, defrosted • 3 tbsp Waitrose & Partners Vegan Original Soft Spreadable • 2 Waitrose & Partners Large Flat Mushrooms, sliced • Handful sage leaves, roughly chopped • 1 unwaxed lemon, zest and a few drops juice