Step 1: Prepare the Tart Shells

1. Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
2. Roll out the puff pastry on a lightly floured surface. Cut it into 6 equal squares for individual tarts or fit it into a 9-inch tart pan for one large tart.
3. If making individual tarts, score a 1/4-inch border around each square to create an edge. Prick the centers with a fork to prevent puffing. Brush the edges lightly with beaten egg for a golden crust, if desired.

Step 2: Bake the Tart Shells

1. Place the pastry squares or tart shell on the prepared baking sheet. Bake for 10 minutes, or until lightly golden and puffed. Remove from the oven and press down the centers gently with a spoon to make room for the filling.

Step 3: Prepare the Mushroom and Shallot Filling

1. Heat olive oil and butter in a large skillet over medium heat. Add the sliced shallots and cook for 3-4 minutes until softened and slightly caramelized.
2. Add the mushrooms, garlic, thyme, smoked paprika (if using), salt, and black pepper. Cook for 6-8 minutes, stirring occasionally, until the mushrooms are tender and golden. Remove from heat and set aside.

Step 4: Prepare the Goat Cheese Mixture

1. In a small bowl, mix the softened goat cheese with heavy cream until smooth and spreadable. Stir in the parsley, chives, salt, and black pepper. Adjust the seasoning to taste.

Step 5: Assemble the Tarts

1. Spread a layer of the goat cheese mixture onto the baked tart shells, staying within the edges.
2. Top the cheese layer with the mushroom and shallot mixture, dividing it evenly among the tarts.

Step 6: Bake the Assembled Tarts

1. Return the filled tarts to the oven and bake for another 10-12 minutes, or until the pastry is golden brown and the filling is warmed through.
2. Remove from the oven and let cool slightly before garnishing with fresh parsley or thyme.