Season the beef stew meat with the salt, black pepper, and onion powder, tossing the pieces so the seasoning coats them evenly.

Place a large, heavy-bottomed pot or deep skillet over medium-high heat and add the olive oil, allowing it to heat until it shimmers.

Add the seasoned beef to the hot pot in a single layer and cook, stirring occasionally, for 5–7 minutes, until the pieces are well browned on the outside. If needed, brown the beef in two batches to avoid overcrowding.

Reduce the heat to medium and push the browned beef to one side of the pot, leaving some open space on the bottom.

Add the unsalted butter to the open space in the pot and let it melt completely.

Sprinkle the all-purpose flour over the melted butter and whisk or stir it into the fat, cooking for 1–2 minutes to form a light roux that will help thicken the sauce.

Slowly pour in about 1 cup of the beef broth while stirring constantly, scraping up any browned bits from the bottom of the pot to build flavor and prevent lumps.

Pour in the remaining beef broth and stir until the liquid is smooth and the beef is evenly distributed in the pot.

Stir in the dried thyme and dried parsley, making sure the herbs are well mixed into the broth.

Bring the mixture to a gentle boil over medium-high heat, then reduce the heat to low, cover the pot with a lid, and let the beef simmer for 15–20 minutes, stirring once or twice, until it is starting to become tender.

After the initial simmer, add the uncooked wide egg noodles to the pot, gently pressing them down into the liquid so they are mostly submerged.

Cover the pot again and cook over low to medium-low heat for 8–10 minutes, stirring occasionally, until the egg noodles are tender and the sauce has thickened into a creamy gravy-like consistency.

Once the noodles are cooked and the sauce has thickened, remove the pot from the heat and let it sit uncovered for 3–5 minutes to allow the sauce to settle and thicken slightly more.

Stir in the sour cream until it is fully combined, giving the beef and noodles a creamy, velvety texture.

Taste the beef and noodles and adjust the seasoning with a little more salt or black pepper if desired.

Sprinkle the chopped fresh parsley over the top as an optional garnish, then serve the beef and noodles hot straight from the pot.