In a large oven-safe saucepan or Dutch oven, heat the pan over medium heat and cook the bacon until it turns crispy and golden brown, about 5-7 minutes. Remove the bacon and set it aside on a plate.

Season the beef with salt and pepper generously, then add it to the skillet with the rendered grease. Sear the beef for 4-6 minutes on each side until it's nicely browned. Remove the beef and set it aside.

In the same pot, add diced onions, carrots, and celery. Sauté over medium heat for 7-10 minutes until they soften and the onion is translucent. Stir in the chopped garlic and red pepper flakes, cooking until fragrant, about 1 minute.

Pour in the beef broth and crushed tomatoes, scraping any browned bits from the bottom of the pot. Add thyme, rosemary, Italian seasoning, bay leaves, and reserved bacon, stirring to combine. Return seared beef to the pot, ensuring it's at least partially submerged in the liquid.

For stovetop cooking, bring the mixture to a boil, then reduce heat to low, cover, and let it simmer for 2-4 hours until beef is fork-tender. If using an oven, preheat to 275°F (140°C) and cook, covered, for the same duration. For a slow cooker, set to LOW for 8-10 hours or HIGH for 4-6 hours.

Once braising time is complete, taste the pot roast and adjust seasoning with salt and pepper. Remove the bay leaves before serving.