Preheat your oven to 400°F. In a small bowl, whisk together 1 tablespoon flour (from the ingredient list), a generous pinch of salt, and 1 teaspoon ground white or black pepper. Toss the diced chuck roast in the flour mixture to coat. In a deep, oven-safe braising dish, heat a bit of oil over medium-high heat. Shake off excess flour and add the coated chuck roast in batches, searing for about 2 minutes per side until browned. Remove finished pieces to a plate and continue searing the rest. Searing in batches lets you get a beautiful caramelization instead of steaming the beef, which adds a lot of flavor.
Bring a large pot of water to a boil. Meanwhile, peel and roughly chop the Yukon gold potatoes. Add the potatoes to the boiling water and cook until fork-tender, about 25 minutes. Once cooked, strain the potatoes and transfer to a large bowl. Add 1/4 cup half & half, 3 tablespoons butter, a generous amount of salt (to taste), and 1 teaspoon ground white or black pepper. Mash well until smooth and set aside. I like to use really creamy Yukon gold potatoes for their buttery texture.
In the same braising dish used for the beef, chop the bacon and cook over medium heat until crispy. Pour in about 1/4 cup beef broth to help deglaze the pan, scraping up all those delicious browned bits. Then add the chopped carrots and diced onion. Cook for 5-6 minutes, stirring occasionally. Add in the minced garlic, chopped parsley (reserve a little for garnish), and sprigs of fresh thyme. Stir everything together to combine.
Return the seared beef from Step 1 to the pot with the vegetables. Add in remaining beef broth and red wine. Tuck in the bay leaves and bring the mixture to a gentle simmer for about 10 minutes. Meanwhile, whisk together 2 tablespoons melted butter and 1 tablespoon flour to make a slurry. Stir this slurry into the pot to help thicken the stew. Season with additional salt and pepper to taste. Cover the braising dish and transfer to the oven. Bake for 1 hour and 15 minutes. I always make sure to check for seasoning before popping it in the oven to lock in those flavors.
While the stew bakes, bring a small pot of water to a boil. Add the pearl onions and blanch for 2 minutes, then transfer to an ice bath to loosen their skins. Peel the first layer off and set aside. Dice the cremini mushrooms. In a skillet, melt 2 tablespoons unsalted butter and add a splash of oil. Sear the prepared mushrooms and blanched pearl onions together until the mushrooms are browned and the onions are tender. Season with a little salt and a squeeze of lemon juice at the end. I like to add a bit of lemon juice here because it really brightens up the flavor of the rich stew.
After about 1 hour in the oven, remove the braising dish and stir in the sautéed pearl onions and mushrooms from Step 5. If the stew looks dry, add a splash of beef broth. Cover and bake for an additional 25 minutes. (Optional: Remove the dish from the oven and shred some of the beef if desired—this makes for an easier, more homestyle feel.) Using an ice cream scoop or spoon, add generous mounds of mashed potatoes from Step 2 over the top of the beef mixture. Brush the top with 2 tablespoons melted butter, then return dish to the oven and bake at 400°F for 20 minutes. Broil for just a few minutes at the end to get a nicely browned top. For a really golden crust, I sometimes sprinkle a touch of extra butter or flaky salt right before broiling.
Remove the dish from the oven and let it cool for a few minutes. Finish with chopped chives and the remaining fresh parsley. Enjoy your savory beef and mashed potato bake! I like to add generous fresh herbs just before serving for a pop of color and freshness.