Roasted Prime Rib with Sauteed Mushrooms and Mom's Creamy Horseradish Sauce

INGREDIENTS

• 6 tablespoons lemon juice
• 6 tablespoons fresh parsley, chopped
• salt and pepper, to taste
• 3 cloves garlic
• 4 tablespoons unsalted butter
• 2 lbs mushrooms, washed, dried, and if large, chopped
• 2 tablespoons olive oil
• FOR THE MEAT:
• 1/2 cup olive oil
• 1-2 tablespoon Worcestershire sauce
• 1 cup heavy cream
• 2 tablespoons fresh thyme leaves
• 1/2 teaspoon salt
• 2 tablespoons kosher salt
• 3 teaspoons ground black pepper
• 4 tablespoons grated horseradish
• FOR THE HORSERADISH SAUCE:
• 1 ( 8lb) standing rib roast, trimmed (to multiply or divide the recipe,this translates to roughly 1 rib for every 2-3 people)
• 1/4 teaspoon paprika
• 2 cloves garlic, finely chopped
• 1/4 teaspoon cayenne pepper
• 2 tablespoons fresh rosemary leaves
• FOR THE SAUTEED MUSHROOMS:
• 2 medium shallots