Preheat your oven to 400 degrees.
In a large bowl, using an electric mixer, combine the flour and salt. Add the butter and mix on medium speed until dough becomes crumbly and the butter is broken down to small bits. Continue to mix and add water, one tablespoon at a time. When you are able to pinch the dough and it holds together, it's done.
Remove dough from the mixer and place on a clean, lightly floured surface. Gently knead the dough until it forms a smooth dough. Don't over do it. You should be able to see little bits of butter through out the dough.
Divide the dough in half and shape into 2 flat rectangles. Wrap the rectangles in plastic wrap and refrigerate for half an hour.
While the dough is cooling, get your cheese mixture ready, In a medium bowl, combine the cream cheese and confectioner's sugar until creamy. Mix in the vanilla paste, pinch of salt and lime juice. Once the cheese mixture has been combined, place it in the refrigerator to harden up slightly while you roll out the dough.
Place a large piece of parchment paper down on your work surface, sprinkle some flour over the top and place an unwrapped rectangle of dough in the center. Using a rolling pin that's been dusted with flour, roll the dough out so that your dough is about ⅛ of an inch thick.
Be sure to occasionally peel the dough from the parchment paper and dust with flour to ensure it doesn't stick. The finished product should be a rectangle-ish shape that measures about 10x14 inches. The shape doesn't have to be a perfect rectangle, so don't freak out if your dough doesn't form a pristine 10 x 14 rectangle.
Using a small (and sharp) knife or a pizza cutter, trim the dough's edges and cut the dough into 3x5 rectangles, making about 8 rectangles.
Transfer the rectangles to a baking sheet that has been lined with parchment paper, leaving about an inch in-between each.
Once transferred, repeat this process for the second dough rectangle and place in a second, parchment paper-lined baking sheet.
Place one tablespoon of guava marmalade in the center each piece of dough. Pull the cream cheese mixture from the refrigerator and place 1 tablespoons of cheese mix in the center of the rectangle, over the guava.
Beat one egg in a small bowl and brush the edges of the dough with the egg wash, this will act as the glue that keeps the dough together.
Gently place a dough rectangle over the filling and using a fork, lightly press all around the edges.
Once you have covered all of your pop tarts and pressed the edges with a fork, use a tooth pick to prick multiple holes on the top layer of dough.
The pricked holes will act as small ventilators so air doesn't get trapped inside and the pop tarts don't bubble up. Combine the egg yolk you reserved earlier and combine it with a tablespoon of water to create an egg wash.
Then, brush the the dough with the egg wash to get a nice golden color and sprinkle on some granulated sugar over the top.
Place the baking sheets in the middle rack of your oven and bake for 15 minutes until golden brown.
Once the pop tarts are out of the oven let them cool down before eating.