For the onion filling
01 -
2 medium yellow onions, thinly sliced
02 -
1 tablespoon unsalted butter
03 -
1 tablespoon olive oil
04 -
1 teaspoon fresh thyme leaves
05 -
1 teaspoon Worcestershire sauce
06 -
1 tablespoon Dijon mustard
For the sausage rolls
07 -
1 lb (450 g) pork sausage meat, casings removed if needed
08 -
1/2 cup (50 g) shredded Gruyere cheese
09 -
1/3 cup (25 g) plain breadcrumbs
10 -
1/2 teaspoon kosher salt, or less if sausage is salty
11 -
1/2 teaspoon black pepper
12 -
2 sheets frozen puff pastry, thawed but cold
13 -
1 large egg, beaten
14 -
1 teaspoon sesame seeds or flaky salt, optional