Allow puff pastry to come to room temperature according to package directions, usually approximately 40 minutes. Preheat oven to 400° F.
On a floured surface, unroll one puff pastry sheet. Gently press the pocket maker to make marks for 6 pockets. Place 2 tablespoons of strawberry jam on each pocket, being careful not to fill too close to the edge.
In a small bowl, gently mix the egg white. Using a pastry brush, brush the beaten egg white around the inside edge of the pocket to create a tighter seal.
Roll out the second sheet so it’s slightly larger than the first, and place on top of the first sheet. Gently press down around the filling so you can see the shape. Place pocket maker on top, and press down firmly to seal the pocket. Remove excess dough. Place pocket on a cookie sheet using a thin spatula.
Bake at 400 ° F for 15-20 minutes, until golden brown. Remove tray from oven, and allow pop tarts to cool on the cookie tray for a couple of minutes, then remove them to a cooking rack. Once they have cooled spread icing over the top. I garnished mine with pink sprinkles as well.
Place strawberry jam and butter in a small microwavable dish, and heat until melted, about 30 seconds, stirring after each 15 seconds.
Place powdered sugar, vanilla, and salt in a large bowl, and stir in melted jam mixture. Add milk to achieve desired consistency.
Any extra icing may be stored in the fridge or the freezer and microwaved again for a few seconds to bring it back to soft consistency.