Preheat the oven to 300 degrees
Begin by preparing the vegetables; onions, brussels sprouts, carrots, mushroom & garlic. Clean, slice and quarter the veggies and set them aside.
Prepare the beef - I cut off all/most of the fat. Cut the beef into 1 inch cubes. Season well with salt & pepper.
Using a large oven proof stock pot, begin by browning the bacon. Cut it into small pieces (lardons) and turn the heat on medium. Sauté until the bacon is crispy and you've rendered all of the fat from the bacon. Remove the bacon from the pan & drain on paper towels. Retaining the bacon fat.
Next brown the beef in the stock pot. You may need to add more oil to the pan (I used olive oil) - brown all sides, you'll probably need to do this in a couple of batches. When all sides are brown, remove with a slotted spoon and set aside.
Then add the vegetables to the pan - saute' them for 5-7 minutes until you just begin to get some color on the vegetables. After 5-7 minutes, add the thyme, red pepper flakes & tomato paste and saute' for another 2-3 minutes. Add in the beef, red wine, cognac & beef stock. Stir well - place the lid on the stock pot & tuck in the oven. Depending on the cut of meat that you use, it will be done in 2-3 hours. Cook it until the meat is tender.
When the meat is tender, remove it from the oven & place it on the stove over low heat. In a small bowl, combine the softened butter & flour. Using a fork, mash it together until it is completely combined. Add it to the stew while it is hot - the flour/butter mixture will thicken the stew without making the broth lumpy. It's the best way to thicken a stew. Cook it for about 3-4 minutes more and the stew will be done.