Preheat oven to 375º F.
Saute the onion in the butter until translucent
Add all other ingredients (except crusts) and cook until the veggies are heated and no longer frozen, approximately 5 minutes.
Fir the first refrigerated pie crust in your pie plate, pressing to the sides of the pie plate. Leave the top excess hanging over the edge of the pie plate - do not crimp.
Pour the prepared filling into the pie crust.
Top with the second crust and press the two pie crust edges together, crimping to seal.
Prick the top crust with fork to create few air holes in the top crust, piercing the crust 4 - 5 times.
Bake at 375º F for 30-40 minutes, until top crust is golden brown.