Heat your oven to 425° Fahrenheit. Using cooking spray, grease a baking dish.
Add your oil into a skillet, and heat over medium-high heat. Add your beef tenderloin and cook for about 7-minutes per side or until browned on all sides. Reserve the pan.
Add the beef to the greased baking dish, and season with salt and pepper, to taste.
Bake for 32-minutes, then allow cooling for about 10-minutes before slicing.
Now, melt the butter in the reserved pan over medium-high heat. Stir-fry your shallots and garlic for about 1-minute.
Add the wine to pan, then add in the cranberries, thyme, beef stock, and chili flakes. Cook for approximately15 minutes or until the sauce begins to thicken. Season sauce with salt and pepper, to taste.
Serve your roast beef topped with spicy cranberry sauce.
Serve and Enjoy!