Heat the olive oil in a large Dutch oven over medium-high heat. Add the diced bacon and cook until browned, about 10 minutes. Remove the bacon with a slotted spoon and place on a plate.

Pat the beef dry with a paper towel. Season liberally with kosher salt and pepper. Working in batches, sear the beef cubes on all sides. Remove the seared beef and place on the plate with the bacon. Repeat until all the beef is browned.

Add the carrots and onions to the Dutch oven. Season with 1 tablespoon salt and 2 teaspoons freshly ground black pepper. Stir to combine. Continue cooking for 10 to 15 minutes or until the onions are lightly browned. Stir in the garlic and cook until fragrant, about one minute.

Add the Cognac and carefully ignite with a match to cook off the alcohol.

Add the beef and bacon back into the Dutch oven. Pour in the bottle of wine and enough beef broth to just cover the beef. Bring to a simmer and cover with a tight-fitting lid.

Place the Dutch oven in an oven preheated to 250°F. Cook for 1-½ hours or until the meat and vegetables are fork-tender.

In a large pan, saute the mushrooms in 2 tablespoons of butter over medium-high heat for 10 minutes or until lightly browned. Set aside.

In a small bowl, use a fork to combine the flour with 2 tablespoons of butter. Stir into the stew. Then, stir in the frozen onions and sauteed mushrooms. Bring the stew to a boil, then reduce the heat and simmer for 20 minutes. Season to taste with more salt and pepper.

Garnish with chopped fresh parsley and serve with toasted sourdough bread slices.