Preheat the OvenPreheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
Prepare the PastryOn a lightly floured surface, roll out the puff pastry to about 1/8-inch thickness. Cut into 3–4 inch squares or circles. Place on the baking sheet and prick the center of each piece with a fork to prevent puffing in the center.
Cook the FillingIn a skillet over medium heat, heat olive oil and sauté shallots until translucent, about 2–3 minutes. Add garlic and chopped mushrooms. Cook for another 5–7 minutes, until tender and golden. Season with salt and pepper to taste. Let cool slightly.
Make the Cheese MixtureIn a bowl, combine softened goat cheese, sautéed mushroom mixture, and fresh herbs. Mix until well combined and creamy.
Assemble the TartsSpoon the filling into the center of each pastry cutout, leaving a ½-inch border around the edges.
BakeBake in the preheated oven for 15–20 minutes, or until the pastry is golden and puffed.
Cool and ServeAllow the tarts to cool for a few minutes before serving. They can be enjoyed warm or at room temperature. Garnish with extra herbs if desired.