Rinse and chop spinach into bite-sized pieces. Next, finely mince the shallot.
Heat a pan with olive oil over medium-high heat. Add the shallot, cook for about 2 minutes, then add the garlic. Sauté for about 30 seconds.
Add the spinach and a pinch of salt and cook down. Add some fresh pepper. Remove from heat, set aside.
Combine your cream cheese with the feta and Parm in a mixing bowl. Then, add the cooked spinach mixture and one egg yolk. Stir to combine.
Preheat the oven to 450°F
Flour your work surface and place your puff pastry on top. Using a rolling pin, lightly roll out to take out the creases. Next, cut the puff pastry into 3 - 4 inch squares and place on a parchment paper-lined baking sheet.
Add about 2 tbsp of the mixture to each square of puff pastry. Beat one egg in a separate bowl and use that egg wash to brush two edges of the puff pastry. Crimp the egg washed sides together, which will help to hold things together in the oven. Do this for all of your pastries.
Optional: Place entire baking sheet in fridge for 10 minutes
Use the rest of the egg wash and douse each pastry. Cover the top and sides completely.
Bake for about 20 minutes, rotating the baking sheet at 10 minutes. (Note: ours only needed about 12 minutes total, so keep an eye out and consider your own oven characteristics. Ours is super powerful.)
Cool on a wire rack. Serve and enjoy!