Heat 2 tablespoons olive oil in a large skillet over medium heat. Add leeks and saute 2 minutes; stir in beans, broth, 1 tablespoon garlic, and thyme. Cover, reduce heat to low, and simmer 8-10 minutes. Season with salt and pepper. Transfer bean mixture to a food processor and blend until smooth. Return to skillet, cover to keep warm. Heat remaining 2 tablespoons olive oil in another skillet over high heat, add mushrooms, remaining garlic, and saute 8-10 minutes until caramelized. Season with salt and pepper, then toss in chopped parsley. Spoon mashed bean into shallow bowls. Top with equal portions of mushrooms, then lightly drizzle truffle oil and serve. Makes 8 servings.
Approximate Nutrient Analysis per serving (not including salt to taste or drizzled truffle oil):
170 calories, 7 g fat, 7 g saturated fat, 0 mg cholesterol, 325 mg sodium, 19 g carbohydrate, 5 g fiber, 3 g sugar, 8 g protein