Instructions: Prepare the Cake Batter: In a mixing bowl, prepare the yellow cake mix according to the instructions on the box. Add vanilla extract to the batter and mix well.
Bake the Cake Base: Grease a 9x13 inch baking dish. Pour the prepared cake batter into the greased dish, spreading it out evenly.
Prepare the Strawberry Filling: In a saucepan, combine the sliced strawberries, granulated sugar, cornstarch, and water. Stir well to combine. Cook over medium heat, stirring constantly, until the mixture thickens and the strawberries soften, about 5-7 minutes.
Assemble the Pie Cake: Once the cake base is baked and slightly cooled, pour the strawberry filling over the cake, spreading it out evenly.
Bake Again: Place the baking dish back into the oven and bake for an additional 10-15 minutes, or until the edges of the cake are golden brown and the strawberry filling is bubbly.
Cool and Serve: Allow the pie cake to cool slightly before slicing and serving. You can serve it warm or at room temperature, with a dollop of whipped cream or a scoop of vanilla ice cream on top if desired.