01 -
Heat oil in a large wide saucepan over medium-high heat. Cook mushrooms for 8–10 minutes until their released moisture mostly evaporates. Add onion and carrots; cook for 6–8 minutes until beginning to soften.
02 -
Stir in garlic and thyme for one minute. Sprinkle over flour and stir for one minute, coating the vegetables.
03 -
Gradually stir in broth, then cream. Add lentils and black pepper and simmer for five minutes, stirring, until the filling is thick but spoonable. Transfer to a 2-litre pie dish and leave for 15 minutes to stop steaming heavily.
04 -
Heat oven to 200°C / 400°F. Lay the cold pastry over the dish and trim to leave a small overhang. Press onto the rim, crimp the edges and cut a small steam slit in the center.
05 -
Brush pastry lightly with beaten egg. Bake for 25–30 minutes until the lid is puffed, deeply golden and cooked underneath, and the filling bubbles at the edges. Place a tray beneath to catch drips.
06 -
Rest for 10 minutes. Spoon filling into six bowls with a piece of crisp pastry on each. This is a soft pot-pie filling rather than a sliceable pie.
07 -
Refrigerate leftovers within two hours for up to three days. Reheat in the oven until the filling is piping hot throughout, loosely covering the pastry if it browns too much.