Duck Liver Pâté with Blackberry Conserva

Name: Duck Liver Pâté with Blackberry Conserva
Ingredients: 14 ounces duck livers (about 1 1/4 cups); 1 tablespoon plus 1/4 teaspoons kosher salt, divided; 1/2 cup plus 2 tablespoons unsalted butter (5 ounces); 1 medium-size yellow onion, thinly sliced; 10 fresh sage leaves; 1/3 cup Champagne or dry white wine; 1/3 cup duck fat, melted; 2 pounds fresh or frozen blackberries; 5 tablespoons granulated sugar; 2 tablespoons water; 4 thyme sprigs; 3 whole cloves; 1/8 teaspoon kosher salt; Pinch of black pepper; Grilled bread slices and whole-grain mustard, for serving