Prepare the beef: Remove the dried chipped beef from the package. Stack the slices and cut into thin strips or small pieces. If the beef tastes very salty, rinse briefly under cool water and pat dry with paper towels.
Toast the bread: Toast the bread slices until golden and crisp. Spread lightly with softened butter, if desired. Keep warm while you make the sauce.
Make the roux: In a large skillet or medium saucepan, melt the butter over medium heat. Sprinkle in the flour and cook, stirring constantly, for 1 to 2 minutes until smooth and bubbly but not browned.
Add the milk: Turn the heat to medium-low. Slowly pour in about ½ cup of milk while whisking constantly. When smooth and thick, add the remaining milk in small amounts, whisking until the sauce is smooth and lump-free.
Season and thicken: Stir in the onion powder, garlic powder, black pepper, and smoked paprika or cayenne, if using. Bring to a gentle simmer over medium heat, stirring often, until the sauce has thickened enough to coat the back of a spoon, about 4 to 6 minutes.
Add the beef: Stir the sliced dried beef into the sauce. Reduce the heat to low and simmer for 3 to 5 minutes, until the beef is heated through and the flavors blend. Taste and add salt only if needed.
Serve: Place one or two slices of warm toast on each plate. Spoon the creamed chipped beef over the toast, letting some sauce run over the edges. Garnish with parsley or chives, if using, and serve immediately.