Preheat oven to 400°F and line a baking sheet with parchment.
Place beef in a bowl and season with salt and pepper.
Add onion/shallots, garlic, Worcestershire, breadcrumbs/panko, egg, blue cheese, horseradish, parsley and olive oil.
Mix to combine and let chill for a few hours to develop flavors.
Sauce - combine all ingredients in bowl and let stand for breadcrumbs to soften. Adjust salt and pepper to taste. (If using fresh apples, peel, seed and place in VitaMix . Blend on a low speed until it's applesauce. Add in the rest of the ingredients, blend on low for a few seconds and then turn to high just for a second.) Place in refrigerator to chill.
Roll large, walnut-sized balls using oiled hands or a small scoop and place on a parchment-lined baking sheet.
Roast to golden and crisp, about 30 minutes.