Preheat oven to 325 degrees (300 convection). Pat the beef chuck meat dry and sprinkle with salt and pepper.
Heat olive oil in a large dutch oven. Add bacon and cook oven medium heat, stirring occasionally until bacon is crisp, about 8 minutes. Remove bacon to a plate with a slotted spoon, leaving the bacon fat in the dutch oven.
Add half of the beef to the dutch oven and cook on all sides until browned, about 5 minutes. Using the slotted spoon, place beef on the plate with the bacon. Repeat with the second batch of beef. Set aside. Leave grease in bottom of dutch oven.
Place all the carrots and onions into the dutch oven along with 1 1/2 tsp salt and 1 tsp of pepper. Sauté vegetables over medium heat until onions start to soften and brown, about 8 minutes. (If bottom of the pan starts to burn in spots, add a couple of tablespoons of water into the vegetables). Add the garlic and cook until fragrant, about 1 minute. Add the cognac (carefully) and reduce it by about half to burn off the alcohol. Make a well in the center of the vegetables and stir in the tomato paste and thyme. Cook 1 minute. Add the beef and bacon back into the dutch oven. Stir in the red wine and just enough beef broth to just get to the top of the meat. Raise heat and bring mixture to a boil. Cover the pot with a tight fitting lid, and place in the oven.
Bake stew for 2 hours, stirring halfway through.
Meanwhile, if adding mushrooms : Heat 1 Tbsp butter in skillet over medium heat. Saute mushrooms until they just start to release their liquid, about 6-7 minutes . Set aside. Add them to stew in the last 30 minutes of baking.
Remove stew from the oven. In a small bowl, mash together 2 Tbsp softened butter and 3 Tbsp flour until a smooth paste is formed. Stir the paste into the stew, and put the stew back in the oven for 15 minutes to thicken. Remove from oven and let rest uncovered for 15 minutes, and then serve.
Enjoy!