Begin by thawing your puff pastry until it's pliable, then roll out each sheet on a lightly floured surface to about 1/16 inch thick. Use a fork to prick the surface of the pastry to prevent it from puffing too much during baking.

Using a biscuit cutter, cut out approximately 30 circles from the rolled pastry and gently transfer them onto a parchment-lined baking sheet.

Top each pastry circle with about 1 teaspoon of Gruyère cheese, then add one or two slices of ripe tomatoes, followed by a sprinkle of kosher salt, black pepper, and chopped thyme.

Preheat your oven to 400°F (204°C) and bake for 20-25 minutes or until golden.

Remove from the oven and allow to cool slightly before serving.