Preheat oven to 375 degrees Fahrenheit. Line a rimmed baking sheet with parchment paper and set to the side.
In a small bowl, prepare the egg wash by beating together the egg with a tablespoon of water and set aside. In a separate small bowl, mix together the cream cheese, cinnamon, and vanilla. Set to the side.
On a lightly floured surface, roll one sheet of puff pastry into an 8-by-12-inch rectangle, about the size of a standard sheet of paper. If using cookie cutters, cut out your desired shapes and set aside on the parchment lined baking sheet. If not using cookie cutters, use a sharp knife or pizza cutter and slice the pastry into 8 rectangles, measuring approximately 3 x 4 inches (it’s okay if it’s not exact, just an estimate here). Place the cut puff pastry onto your parchment lined baking sheet. These will be the bottom layer of your puff pastry for the pastelitos.
Repeat with the second sheet of puff pastry and keep on your floured work surface. These will be the top layers of your puff pastry for the pastelitos.**
Dip a pastry brush into the egg wash and gently paint the edges of your bottom layer of cut puff pastry. Lay a small slice of guava paste in the center of each piece of cut puff pastry. You can also mold the guava paste with your fingers to flatten and shape before placing in the center of the cut puff pastry.
Spread a small dollop of the cream cheese on top of the guava paste (about 1 tablespoon cream cheese per cut puff pastry). Top with the second layer of cut puff pastry.
Using the side of your index fingers, press around and between the mounds of filling, pressing out any excess air, to glue the top puff pastry to the bottom. Using a fork, crimp the edges to seal the pastry together. Gently brush the top of each pastry with the egg wash. Sprinkle the surface with turbinado sugar.
Bake the pastries until puffed and golden brown, about 15 to 20 minutes. Serve warm or at room temperature.
Store any uneaten pastries in an airtight container for up to 2 days.