01 -
2 big yellow onions (about 2 whole large or 4 smaller ones).
02 -
A small handful of fresh thyme sprigs.
03 -
2 minced garlic cloves.
04 -
6 oz Gruyère cheese, shredded.
05 -
1/2 cup of panko crumbs.
06 -
Half a cup of 2% or whole milk.
07 -
An egg, large size.
08 -
2 teaspoons of Worcestershire sauce.
09 -
2 1/2 teaspoons kosher salt.
10 -
3/4 teaspoon ground black pepper.
11 -
1 1/2 lbs ground beef.
12 -
2 tablespoons butter, unsalted.
13 -
2 tablespoons plain flour.
14 -
1/2 cup dry white wine.
15 -
14.5 oz beef stock.
16 -
1 teaspoon vinegar (sherry or balsamic works).