Start by thawing the puff pastry according to the package instructions until it becomes soft but still cold. Place the pastry sheet on a lightly floured surface and gently roll it out slightly. Cut the pastry into equal rectangles or circles depending on your preferred tartlet shape.
Line a baking sheet with parchment paper to prevent sticking and make cleanup easier later. Transfer the pastry pieces onto the tray while leaving some space between each tartlet. Use a fork to prick the center of each pastry piece while leaving a small border around the edges.
Wash and dry the tomatoes carefully before slicing them into thin, even rounds for consistent cooking. Thin slices help reduce excess moisture and keep the pastry crisp while baking. I like placing the tomato slices on paper towels for a few minutes to absorb extra liquid.
Spread goat cheese gently over the center of each puff pastry piece without covering the borders. The creamy cheese layer acts as a barrier that helps prevent the pastry from becoming soggy. Sprinkle minced garlic, thyme, salt, and black pepper evenly over the cheese.
Layer the tomato slices neatly over the cheese mixture while slightly overlapping them for a pretty presentation. Drizzle olive oil lightly over the tomatoes to help them roast beautifully in the oven. Finish by sprinkling grated parmesan cheese over the top for extra flavor.
Crack the egg into a small bowl and whisk it until smooth for the egg wash mixture. Use a pastry brush to coat the pastry edges lightly with the egg wash. This step helps create a beautiful golden-brown crust during baking.
Place the tray into a preheated oven at 400°F (200°C) and bake until the pastry becomes puffed and golden. The tomatoes should look slightly roasted while the cheese becomes creamy and melted. Baking usually takes about 20 to 25 minutes depending on your oven.
Remove the tartlets carefully from the oven and allow them to cool slightly before serving. Sprinkle fresh basil over the warm tartlets for a fresh and colorful finish. I love serving them warm because the pastry stays extra flaky and delicious.