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

Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add sliced yellow onions and cook for 15 to 20 minutes until caramelized.

In another skillet, heat 1 tablespoon of olive oil over medium-high heat. Add cubed butternut squash and sauté for 10 to 15 minutes until tender.

In a mixing bowl, combine caramelized onions, sautéed butternut squash, fresh thyme, salt, and pepper.

On a floured surface, roll out the puff pastry, place it on the baking sheet, and spread the filling evenly, leaving a border. Crumble goat cheese on top.

Bake the tart in the oven for 25 to 30 minutes until golden brown.

Allow the tart to cool on the baking sheet for 10 minutes before slicing.