In a saucepan over medium heat, melt butter, then add flour and whisk for 1 minute.
Slowly add beef stock, whisking continuously.
Stir in Worcestershire sauce and beef base.
Simmer for 10 minutes, stirring occasionally, then cover and set aside.
Resting the Roast & Prepping the Yorkshire Pudding Pan
Remove the roast from the oven and tent loosely with foil. Rest for 30 minutes.
Place a 12-count muffin pan in the oven and preheat to 500°F (260°C).
Once hot, spray liberally with pan spray (or use beef fat).