For the strawberry filling, place all ingredients, fresh strawberries, sugar, kosher salt, lemon zest, lemon juice and water in a saucepan. Turn heat to medium.
Bring the mixture to a boil, stirring every minute or so. When it comes to a boil, reduce the heat to a simmer. It will start to release juices and the fruit will begin to soften.
Cook for up to 30 minutes. The longer you go, the smoother and more jam-like it will be. Store in the fridge and eat within a few days.
Repeat method for blueberry jam.
Pop Tarts
Preheat the oven to 350°F.
Take your thawed puff pastry and cut each sheet into 6 rectangles. Evenly fill half of the rectangles with the chilled strawberry or blueberry jam.
Lay the remaining 6 rectangles over the filling and seal the edges by crimping with the back of a fork. Repeat until you have 6 tarts.
Place on parchment-lined baking sheets and brush the tops of the tarts with water. Place in oven and bake the tarts for 15 to 20 minutes or until puffed and deep golden brown. Let cool slightly.
Whisk together the milk, powdered sugar and jam of choice. If needed, add 1 tablespoon of milk or jam at a time to thin the glaze as desired. Drizzle the glaze over pop tarts, add sprinkles if preferred and allow to set at room temperature. Enjoy!