Prepare the pie pan with the crust (homemade or storebought)

In a medium saucepan, add the blackberries, salt, sugar, butter, and cornstarch and cook on medium heat until the mixture thickens. (about 10 minutes)

Add the thickened blackberry mixture to a 9x13 inch pan

Adjust the top layer of crust over berries, or break the crust into chunks and add that over the berry mixture

Bake at 450 for 10 minutes, then lower the temperature to 350 and bake for 30 more minutes.