Finely dice the onion and the garlic. Chop or tear the spinach. Pre-heat your oven to 200°C/390°F. Place a silicone mat or baking paper on a baking sheet.
In a pan, heat up a little oil and add in the spinach. Sauté until the spinach has wilted. Place a colander over a bowl and put the spinach in the colander. Squeeze out all of the liquid using a spoon or your hands. Put the spinach in a larger bowl.
In the same pan as before, add in a bit more oil and sauté the onion and garlic until the onion is soft and translucent. Then add in the vegan bacon and cook until the vegan bacon is crispy. Drain out most of the oil and add to the spinach. It's best to wait until everything is completely cooled.
Add the vegan cream cheese, a pinch of salt, and a pinch of pepper. Mix together until everything is combined.
Roll out your puff pastry and cut into squares. Add approximately 1 teaspoons to each square. Add a little bit of vegan feta cheese on each square. Pinch 2 sides together and make sure it's really closed. Puff pastry has a tendency to open while in the oven. Fold the pinched sides over to one side and roll up the end. Brush with a little bit of unsweetened vegan milk or with some oil. Bake in the oven for about 20 minutes, or until golden brown and crispy.