Line large baking sheet with parchment paper.
In food processor, combine flour, sugar, butter, & salt.
Pour mixture into large mixing bowl & add in one egg yolk.Knead with your hands until smooth.
Let sit in refrigerator for 1.5 hours. Preheat oven to 360 F.
Mix in extra egg yolk to dough. Add 1 tbsp of water as needed to help dough stick together. Place dough on large cutting board & roll out until about 1.5 cm in height.
Cut dough into even number of rectangles.
Place half of the rectangles on parchment paper & place 1 tsp of filling directly in center of dough.
In separate small bowl, combine egg yolk & water.
Brush the edges of filled dough with egg & water mixture.
Place evenly sized dough on top of filled dough & press down on sides to close.
Press the edges of the dough with a fork to secure rectangles together.
Bake for 20-30 minutes until golden brown.
If topping with cheese, immediately cover & add on toppings. If topping with cream cheese, let pop-tarts cool & cream cheese soften. Top to your desire, serve, & enjoy!