Meat Loaf with Sour Cream-Mushroom Sauce

Name: Meat Loaf with Sour Cream-Mushroom Sauce
Prep time: 35 min
Total time: 35 min
Cuisine: American
Ingredients: 0.33333334326744 cup fat-free milk; 2 egg whites; 1 cup soft whole-grain bread crumbs (1 1/3 slices bread); 0.25 cup chopped green onions; 2 teaspoons dried Italian seasoning, crushed; 0.25 teaspoon salt; 0.125 teaspoon ground black pepper, plus more for garnish; 1 pound lean ground beef; Nonstick cooking spray; 1 tablespoon butter; 1.5 cups sliced fresh mushrooms; 1 clove garlic, minced; 0.25 cup thinly sliced green onions, plus more for garnish; 1 (8 ounce) container light sour cream; 2 tablespoons all-purpose flour; 0.75 cup cold water; 2 teaspoons instant beef bouillon granules