Slow-Cooked Beef & Button Mushrooms Pie

What is it?

Beef chunks are slow-cooked sous vide with button mushrooms in a rich gravy, then tucked into pastry for baking. The filling leans on large pieces of beef rather than mince, with mushrooms bringing an earthy note and a softer texture. Herbert Adams uses the same sous vide approach across this range, but this version swaps the plain beef filling for mushroom and gravy. It’s a frozen pie, so it goes from the freezer to the oven rather than the microwave, and it’s built to be eaten hot, with the sauce thickening as it bakes.