Ahh, Pillsbury strikes again! I subscribe to their e-newsletter, and I'm always seeing fabulous recipes. Like this one. Except, the recipe called for deli roast beef, and I felt that was too expensive, so we did up a roast using our own recipe. It's called "Pot Roast in Foil". I'll try to post it right away, so if you want to sass up your roast recipe, it'll be available.
The roast beef recommended was from the deli. I recommend using leftover roast instead.
Heat oven to 425*F. Make pie crusts as directed on box for Two-Crust Pie using 9" pie pan.
In 3 quart saucepan, mix gravy and cornstarch until well blended. Stir in Worcestershire sauce, frozen vegetables, and mushrooms. Cook over medium-high heat, stirring occasionally, until bubbly. Stir in roast beef. Pour into crust-lined pan.
Top with second pie crust; seal edge and flute. Cut decorative slits in several places in top crust to allow steam to escape.
Bake 15 minutes. Cover crust edge with strips of foil to prevent excessive browning; bake 15 - 30 minutes longer, or until crust is golden brown and filling is bubbly.