Preheat the oven to 180°C. Coat the butternut squash slices and the red onion in oil.
Place on a heavy baking tray and roast for 12-15 mins until just tender. Leave to cool slightly and increase the oven temperature to 200°C.
Next make the salsa verde: blitz the herbs, oil, seasoning & garlic together with a hand held blender or in a food processor. It can be left a little chunky or blitzed until very smooth.
Line two baking trays with baking parchment. Roll the pastry out into a large rectangle before cutting it evenly into 6 pieces.
Turn the pastry over, then place on the baking trays. Use a knife to mark out a 1” border all the way around each tart. Don’t cut all the way through the pastry.
Score the centre square so it doesn’t rise and place the trays in the fridge.
Mix 1/2 the egg, parmesan, cream cheese, herbs and plenty of seasoning into a bowl. Chop the sage and thyme leaves very finely and fold through the cheese mixture.
Use a teaspoon to spread this mixture onto the tartlets - start in the centre of the square and leave the border clean.
Divide the slices of squash and red onion amongst the tarts. Brush the borders with egg wash and bake for 18-20 minutes or until the pastry is puffed up and golden.