Preheat your oven to 400°F (200°C). Gather your ingredients and prepare your tart pan.

Roll out your chilled puff pastry on a lightly floured surface. Press it into the edges of the tart pan and trim excess. Prick the bottom with a fork.

Heat olive oil in a skillet over medium heat. Add finely chopped onions and minced garlic; cook until translucent, about 3-4 minutes. Add the cremini mushrooms and sauté until browned, about 5-7 minutes.

In a large bowl, combine pumpkin puree, ricotta cheese, half of the Parmesan, and eggs. Add the sautéed vegetable mixture and season generously with salt and pepper.

Pour the filling into the prepared pastry shell, smoothing with a spatula. Sprinkle the remaining Parmesan on top.

Place the tart in the oven and bake for 30-35 minutes until golden brown and filling is set. Keep an eye on it during the last few minutes.

Allow the tart to cool for about 10 minutes before slicing. Garnish with pumpkin seeds and serve.