Easy Beef Bourguignonne with Mashed Potatoes

Name: Easy Beef Bourguignonne with Mashed Potatoes
Ingredients: 3 lb. (1.5 kg) beef chuck roast, cut into 1-inch (2.5-cm) cubes; Kosher salt and freshly ground pepper; 1 Tbs. vegetable oil; 1/2 lb. (250 g) bacon, diced; 1 jar Beef Bourguignonne Braising Sauce; 2 cups (6 1/2 oz./200 g) thawed frozen pearl onions; 1/2 lb. (250 g) baby carrots, peeled; 3 lb. (1.5 kg) russet potatoes; 8 Tbs. (1 stick) (4 oz./125 g) unsalted butter, at room temperature; 1/2 cup (4 fl. oz./125 ml) whole milk, warmed; Chopped fresh flat-leaf parsley for garnish