In a large mixing bowl, whisk together the all-purpose flour, sugar, and salt to combine. Cut in the cold unsalted butter until the mixture resembles coarse crumbs. Gradually add ice water, one tablespoon at a time, mixing until the dough holds together. Divide the dough in half, shape into disks, and refrigerate for about 30 minutes.

In a medium saucepan over medium heat, combine the chopped strawberries, sugar, and vanilla extract. Stir occasionally, cooking until the strawberries soften and release their juices, about 5-7 minutes. Once the mixture thickens slightly, remove from heat and let cool.

Roll out one half of the chilled dough on a floured surface into a rectangle that fits your baking dish. Transfer to the greased dish, pressing it into the corners. Pour the cooled strawberry filling over the crust, spreading it evenly. Roll out the second half of the dough, placing it over the filling, and gently press the edges to seal.

Preheat your oven to 350°F (175°C). Cut slits in the top crust for steam to escape. Bake until the crust is golden brown, about 30-40 minutes.

Once baked, remove from the oven and allow to cool in the dish for about 15 minutes. Prepare your vanilla glaze while the pie cools by mixing powdered sugar with milk and vanilla extract. Drizzle the glaze over the pie and sprinkle rainbow sprinkles on top.

Allow the pie to cool completely for easier slicing. Cut into squares or rectangles and serve warm or at room temperature.