In a large, heavy-bottomed Dutch oven, set over medium heat, add diced bacon and cook until crispy, about 5–7 minutes. Once crispy, remove the bacon, leaving the grease in the pot.

Season the beef chuck generously with salt and pepper. In the same pan with the bacon grease, sear the beef chunks until browned on all sides, about 4–6 minutes per side. After browning, remove the beef from the pot and set it aside.

Add diced onion, carrot, and celery to the pot. Sauté these aromatic vegetables for 7–10 minutes, stirring occasionally, until they become tender and the onion is translucent.

Stir in the minced garlic and red pepper flakes, cooking for about 1 minute until fragrant.

Pour in the beef broth and crushed tomatoes, and add thyme, rosemary, Italian seasoning, bay leaves, and the reserved cooked bacon. Stir everything together.

Return the seared beef to the pot, submerging it in the sauce. Cover the pot and either simmer on low heat for 2–4 hours, bake in a preheated oven at 275°F for 2–4 hours, or cook in a slow cooker on LOW for 8–10 hours.

After the cooking time, taste the sauce and adjust seasoning with salt and pepper as needed. Remove the bay leaves before serving.