Using a large skillet over medium-high heat, heat the olive oil. Season the beef with the salt and pepper on both sides and then add the beef to the skillet. You want the oil to be relatively hot so you will hear an immediate sizzle as soon as you add the beef to the skillet. Sear on each side for about 1 to 2 minutes. Remove from the heat and onto a cutting board. Cut into bite sized chunks (but not too small) and place into your slow cooker.
Add the sliced mushrooms, onions, garlic, diced tomatoes, tomato sauce, tomato paste, anchovy paste, beef stock and red wine. Sprinkle on the dried oregano and add in the fresh thyme. Stir well and cook on low for 8 hours, or on high for at least 6 hours.
After about 5 hours, stir in the brown sugar, taste and season with salt and pepper and add some red pepper flakes, if using. Stir well and cook for another hour or so on low heat. The meat will be very tender and flavorful. Before serving, discard the thyme sprigs. Serve over pasta and garnish with freshly grated parmesan cheese.