Warm Caramelized Onion Dip

olive oil

chopped onion (about 2 large onions)

chopped fresh thyme

light sour cream

(about 1 1/2 ounces) grated Parmigiano-Reggiano cheese

1/3-less-fat cream cheese

reduced-fat mayonnaise

salt

freshly ground black pepper

hot pepper sauce (such as Tabasco)

Worcestershire sauce