In a large bowl, whisk flour, sugar, and salt. Add cold butter and cut it into the flour until pea-sized crumbs form. Pour in the ice water slowly, mixing until the dough just comes together. Split into two equal portions, flatten into disks, wrap, and chill for at least 1 hour.

In a bowl, mix strawberry jam, fresh berries, lemon juice, vanilla, and cornstarch. The cornstarch helps thicken the filling so it doesn’t spill over as it bakes.

On a floured surface, roll one dough disk into a large rectangle that fits your baking sheet. Transfer it to the lined sheet pan.

Spread the strawberry mixture evenly across the crust, leaving a 1-inch border around the edges.

Roll out the second dough disk to match the size of the first and gently lay it over the filling. Press the edges together with a fork for that classic Pop Tart look.

Cut a few small slits in the top crust to let steam escape. Brush the top with beaten egg to help it bake to a beautiful golden color.

Bake at 375 F for 30–38 minutes or until the crust is golden and the filling is bubbly.

Let the slab pie cool completely (I know, it’s tough). Mix your icing until smooth and pour it over the cooled pie. Add sprinkles.

Cut into squares and enjoy your giant homemade Pop Tart.