Preheat your oven to 425° F.
Slice your peaches into 1/8-inch thick slices and place them in a bowl. Set them aside.
Make the cream cheese filling by mixing together your cream cheese, 2 tablespoons peach preserves, and 2 tablespoons of fresh thyme. Set aside.
Next, prepare your pastry dough. Whether you're using vegan crescent roll dough or puff pastry dough, place your dough on a lightly floured surface.
Stack 4 pieces of the crescent roll dough on top of each other and, using a rolling pin, roll them out into one rectangular sheet, approximately 16 x 12 inches, so that your sheet is about 1/8-inch thick.
If you're using puff pastry, it will likely already be a sheet, but you will still have to roll it out a bit. Then score the pastry sheet (only if you're using puff pastry) with a sharp knife approximately 1-inch from the edge.
Place your pastry sheet on a rimmed baking sheet lined with parchment paper.
To assemble the peach galette, spread the cream cheese filling so that there is a 1-inch border (or inside the scoring if you're using puff pastry). Next, place the peach slices, slightly overlapping, in one layer on top of the cream cheese filling. Then, fold the edges of the pastry sheet over the edge of the peaches, to form a small crust. Make sure to pinch and crimp the corners securely, to ensure the crust does not unfold when baking.
Whisk together 1 tablespoon of peach jam, together with 2 tablespoons of water. Using a pastry brush, coat the pastry dough and peaches generously. Sprinkle fresh thyme over the peaches.
Place in your preheated oven in the center rack and bake for about 20 minutes, until your crust is golden brown.