Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large skillet, heat 1 tablespoon of olive oil over medium heat, add the sliced yellow onions and sauté for 15-20 minutes until golden brown.

In another skillet, heat the remaining tablespoon of olive oil over medium heat, add the cubed butternut squash and sauté for 10-15 minutes until tender.

Combine cooked onions and squash in a bowl, add fresh thyme, and season with salt and pepper.

Roll out the puff pastry, spread the filling evenly, and crumble goat cheese over the top.

Bake for 25-30 minutes until the pastry is golden brown and filling feels set.

Let the tart rest for 10 minutes before slicing.