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

In a skillet over medium heat, add 1 tablespoon of olive oil and 1 tablespoon of butter. Cook the thinly sliced onion until caramelized, about 15-20 minutes.

In a separate skillet, cook the chopped bacon over medium heat until crispy, about 5-7 minutes.

Roll out the thawed puff pastry on a lightly floured surface and transfer it onto the parchment-lined tray.

In a bowl, combine 1 cup of pumpkin puree with 1 cup of ricotta cheese and season with salt and pepper.

Spread the pumpkin-ricotta mixture over the puff pastry, leaving about a 1-inch border. Layer the caramelized onions and crispy bacon on top.

Brush the sage leaves with melted butter and arrange them atop the tart.

Fold the edges of the puff pastry inward toward the filling and brush the edges with the beaten egg.

Bake the tart in the preheated oven for 20-25 minutes until golden brown.

Cool for at least 10 minutes before slicing and serving warm.