In a medium sauce pan over medium high heat, brown the ground beef. Season with a little salt and pepper. Drain excess grease and set aside. Melt butter in the same sauce pan. Add flour and stir until butter/flour mixture is bubbly.
Add milk, salt, and pepper. Stir constantly until thick and bubbly. Add meat and stir. Taste and adjust seasoning as needed (I usually like a bit more pepper). If necessary, add a little more milk until it reaches your desired consistency.
Serve over toast.
Note: this is the exact same recipe I use for sausage gravy. Instead of ground beef, I substitute with hot, ground breakfast sausage.