01 -
2 tablespoons butter, divided.
02 -
1 tablespoon olive oil, divided.
03 -
2 large white onions, thinly sliced.
04 -
1 tablespoon balsamic vinegar.
05 -
2 chicken breasts (500g total).
06 -
½ teaspoon salt.
07 -
¼ teaspoon dried thyme.
08 -
¼ teaspoon black pepper.
09 -
¼ teaspoon garlic powder.
10 -
1 tablespoon plain flour.
11 -
1 cup beef stock.
12 -
½ teaspoon worcestershire sauce.
13 -
100g gruyere cheese, grated.
14 -
Fresh chives for garnish.