Preheat the oven to 250 degrees F.
Heat the olive oil in a large Dutch oven.
Add the bacon and cook over medium heat for 10 minutes, stirring occasionally, until the bacon is lightly browned.
Remove the bacon with a slotted spoon to a large plate.
Use paper towels to dry the beef cubes.
Season with salt and pepper.
Sear the beef in batches in the hot oil 3-5 mins, cooking all sides.
Remove to the plate with bacon and cook all the beef this way.
Add the carrots, onions, 1 tablespoon of salt and a sprinkle of pepper to the pot.
Cook 10 mins.
Add garlic for one minute.
Add the cognac slowly and let it cook off a minute or two.
Return the beed and bacon to the pot.
Add wine, broth, tomato paste and rosemary.
Bring to a simmer and cover.
Place in the oven for 1 1/4 hours.
While it cooks, saute the mushrooms in 2 tablespoons of butter for 10 minutes until lightly browned.
Remove pot from the oven and combine 2 tablespoons of butter and the flour with a fork and stir into the stew. Add mushrooms, too.
At this point I returned to the oven at 300 for an additional 90 mins-2 hours until the beef was completely soft.