Preheat the oven to 300 degrees. Heat half the olive oil in a large Dutch oven over medium-high heat.
Season both sides of the chuck roast well with sea salt, freshly cracked pepper, and garlic powder to taste. Sprinkle the flour over each side of the roast.
Place the roast into the HOT Dutch oven and brown on all sides for a few minutes, until all sides are seared. Remove from the Dutch oven and place on a plate covered loosely by tin foil. Set aside.
Heat the remaining olive oil in the Dutch oven. Add the onions and cook, stirring occasionally, for 3-4 minutes. Add the mushrooms, fresh thyme, and crushed red pepper flakes. Cook, stirring occasionally, for 3-4 minutes.
Add the minced garlic and cook, stirring constantly, for 1 minute. Add the broth and season with sea salt and freshly cracked pepper, to taste, then cover with a lid and place into the oven for 3 1/2 hours, making sure to gently flip the roast over every 45 minutes.
Remove from the oven and let the roast rest on a platter with a tin foil tent.
Spoon out the grease from the top of the liquid and discard. Place the Dutch oven back on the stovetop over medium-high heat.
Cook, stirring occasionally until the liquid is reduced by half. Taste and season with sea salt and freshly cracked pepper, to taste.
Place the roast back into the sauce, to coat. Remove roast and slice before placing on a serving plate.
Spoon the sauce over the top of the sliced roast then sprinkle the top with fresh parsley. Serve immediately. Enjoy.