Leftover pork, store-bought pie crusts, and a gravy built in one saucepan. That is a whole pot pie with about ten minutes of actual work in front of it.

This exists to use up what is left of a roast, and it does that job better than sandwiches do. Three cups of cooked pork, shredded or cubed, disappears into a thyme and Dijon gravy under a golden double crust.

The roux comes first

Four tablespoons of butter melted in a three quart saucepan, then four tablespoons of flour cooked in for two to three minutes.

Equal parts butter and flour, which is the standard ratio for a gravy roux. Those two or three minutes of cooking are what remove the raw pasty taste of flour. Skip them and the finished gravy will taste faintly of uncooked dough underneath everything else.

Then switch from a spoon to a whisk before the liquid goes in. A whisk breaks up lumps as they form. A spoon pushes them around.

Whisk continually as it thickens

Chicken stock, salt, pepper, minced garlic and Dijon mustard all go in, and you whisk without stopping for four to five minutes until the mixture heats and thickens.

Continually is the word that matters. Roux-thickened gravy forms lumps the instant liquid meets flour that has not been dispersed, and once they set they will not whisk out. Adding the stock gradually while whisking is more forgiving than pouring it in all at once.

The Dijon is not just seasoning. Mustard is an emulsifier and it helps keep the gravy smooth and glossy rather than separating as it sits in the pie.

Then the filling goes in

Thyme, pork and thawed frozen mixed vegetables stirred through with a wooden spoon, and cooked until heated through.

Thawed rather than frozen matters. Frozen vegetables dropped into hot gravy release water as they thaw, which thins the gravy right back out after you spent five minutes thickening it. Thaw them and pat them dry.

Everything here is already cooked, so this stage is only about heating and combining. A few minutes is plenty.

Roll the crust onto the rolling pin

The transfer is where pie crusts tear, and this is the trick.

Roll the pastry loosely around the rolling pin, lift it, position it over the pie pan and unroll it back down. The pin supports the whole sheet so nothing stretches or splits under its own weight.

Press it into the pan and let the excess hang over the sides. Do not trim yet.

Seal it properly

Second crust on top, transferred the same way, then trim the excess with a paring knife and press the edges together with a fork.

Fork tines do two things at once. They physically crimp the top and bottom crusts into each other, and they leave the ridged pattern that makes a pie look finished. Press firmly all the way around, because a seal that opens in the oven lets the gravy boil out.

Cut steam holes

Several slashes in the top crust with a paring knife.

A sealed pie full of hot wet filling turns into a pressure vessel. Steam has to go somewhere, and without holes it will find the weakest point of your seal and blow it open. The holes also let moisture escape so the top crust crisps rather than steaming soft from underneath.

Egg wash for colour

One egg whisked with a tablespoon of water, brushed over the top.

Egg alone browns very fast and can go patchy. Thinned with water it spreads into an even layer and gives a uniform golden shine. This is purely cosmetic and it makes a large visual difference.

If you cut leaf shapes from the trimmings, stick them down with a little water before the egg wash goes on.

Bake on a sheet

375F, forty to forty five minutes, until the crust is golden and the filling is heated through.

The baking sheet underneath is worth using. Pot pies bubble over more often than not, and gravy on the oven floor burns and smokes for weeks afterwards.

Cool twenty minutes

This is not optional if you want clean slices.

Straight from the oven the gravy is liquid and a cut slice collapses into a puddle. Twenty minutes lets it set enough to hold. Eight servings, around 463 calories each, and it keeps five days refrigerated.

Freezing it

Freeze after baking, either whole or in individual portions, for up to two months. Thaw overnight in the refrigerator and reheat uncovered at 350F until hot through. Reheating uncovered is what keeps the crust from going soggy.

Using other leftovers

Chicken, turkey and beef all work in place of pork with no other changes. Beef is better with the Dijon swapped for a teaspoon of Worcestershire, and turkey suits sage more than thyme.