Duck Liver Mousse with Caramelized Onions

Name: Duck Liver Mousse with Caramelized Onions
Ingredients: 1 cup minced shallots; 2 teaspoons minced garlic; 1 tablespoon fresh thyme, minced; 1 3/4 teaspoons salt; 1/2 teaspoon freshly ground white pepper; 1/4 cup cognac; 12 ounces cream cheese, at room temperature; 1/2 pound unsalted butter, at room temperature, plus 2 tablespoons; 2 large onions, thinly sliced; 2 teaspoons sugar; Toasted croutons or sliced French bread, for serving; 1 1/2 pounds duck livers, cleaned, rinsed, and patted dry; 1 cup whole milk; 6 slices bacon