In a large bowl, combine the flour and salt. Cut in the butter with the flour mixture using a pastry blender (or a food processor) until the mixture resembles coarse crumbs. Some larger pieces are totally ok. Next, add the egg yolks and 4 tablespoons of the ice water and stir (or pulse if using food processor) until the dough just comes together, adding the additional 2 tablespoons of water if necessary. The humidity of the day will determine how much you need to hydrate the dough.
Divide dough in half and pat each into rough square shapes. This will make it easier to roll out into a rectangle later and yield less waste. Cover in plastic wrap and chill in the fridge at least two hours or overnight, ideally.
Next, add the chopped white chocolate to a bowl and set aside. In a small saucepan, bring the heavy cream to a bowl, then pour over the white chocolate and let it stand for about 5 minutes. Using a rubber spatula, gently stir the white chocolate and cream mixture together. The heat from the cream should have melted the white chocolate completely. Add in the butter cubes and stir until combined. Then, add in the almond extract, vanilla bean paste, and salt and mix again to combine. Add in the sprinkles and mix to combine.
Pop the bowl in the fridge to firm up, about 20-30 minutes. When the ganache is firm but still scoop-able, use a cookie scoop or tablespoon and measure out heaping tablespoon-sized dollops onto a parchment or wax paper-lined plate or tray. Place the ganache dollops in the freezer and freeze for at least two hours. Due to the high sugar content, the ganache will not freeze completely solid but should get quite firm. Store in freezer until ready to assemble pop tarts. You can do this step the day before you make the pop tarts.
Preheat oven to 350 F. Working with only one disk of dough at a time (leave the other in the fridge), roll out onto a lightly floured work surface into a large rectangle about an 1/8th of an inch thick. We want to end up with a 12 x 9 inch rectangle with straight edges so make it just large enough to trim it down to this size. Trim the edges using a ruler or something with a straight edge and a pizza cutter or sharp paring knife. Cut the rectangle into 3 x 4 inch rectangles. Transfer the rectangles to a parchment-lined baking sheet, spacing them about an inch apart. Pop in the freezer while you repeat with the second disc of dough.
Next, whisk the egg up in a small bowl then pull out the first batch of rectangles from the freezer and brush the all the edges with egg wash, about ½ an inch in on all sides. Take the ganache dollops out of the freezer and flatten them out gently with your palms a little so they’re a flat disk. Place a disk in the center of each bottom pop tart. Top with another rectangle. Press the sides down firmly with your fingers then crimp the sides with a fork to enclose the tarts. Then using a fork or toothpick, poke a few holes on the top to allow steam to escape while they bake. Repeat with the rest. Bake for about 25-30 minutes, until crust is golden brown. Allow to cool before glazing. The longer the centers have time to cool down and set up, the firmer the filling will become again too.
To make the glaze, whisk together the powdered sugar and heavy cream, adding more if needed to achieve the desired consistency. It should be drizzlable but still fairly thick, like honey. Drizzle the glaze over the pop tarts and top with sprinkles. Allow to set then enjoy!