Preheat the oven to 190°C.
Cut the squash into thin wedges while removing the scruffy bits and seeds.
Put the wedges onto a baking tray, rub them with olive oil, season with salt and pepper then bake for about 25-30 minutes until soft.
Let the squash wedges cool, then scrape the flesh into a bowl. Add the minced garlic and chopped rosemary. Season with salt & pepper. Mash with fork or potato masher until it’s smooth.
Unroll the pastry onto a clean work surface, then cut it into 2 or 4 rectangular pieces.
Using a blunt knife, draw a border line 1cm inwards from the edges.
Using a fork, poke the base of the tarts, then spread the squash purée evenly on top, up to the border line.
Cut the red pepper & sun-dried tomatoes into thin slices and arrange these on top the tarts, together with some olives.
Bake for 10-12 minutes in the middle of the oven, until the rims are golden.
Serve warm or at room temperature.