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

Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a skillet. Add sliced onion and sauté for 15-20 minutes until golden brown.

Cook bacon in another skillet over medium heat until crispy, about 6-8 minutes, then drain on paper towels.

Roll out the puff pastry to fit the baking sheet and transfer it onto the parchment-lined sheet.

In a mixing bowl, combine pumpkin puree and ricotta cheese. Season with salt and pepper and mix until smooth.

Spread the pumpkin-ricotta mixture over the puff pastry, leaving a 1-inch border.

Layer caramelized onions and crispy bacon on top of the pumpkin-ricotta mixture evenly.

Brush sage leaves with melted butter and place them on top of the tart.

Fold the edges of the pastry inward, brush with beaten egg for a glossy finish.

Bake for 20-25 minutes until the pastry is puffed and golden brown.

Allow to cool for 10 minutes before slicing and serving warm.