Place an oven rack two-thirds up from bottom of oven. Preheat oven to 400°. Lightly grease 4 (2-cup) ramekins, or 8 (1-cup) ramekins or ovenproof soup bowls. Set aside.
Melt butter in a large skillet over medium-high heat. Add mushrooms, leeks, and garlic; cook, stirring often, 8 minutes or until mushrooms are lightly browned and all liquid has evaporated. Add broth and next 6 ingredients; bring to a boil. Cover, reduce heat, and simmer 10 minutes or until vegetables are tender.
Whisk together cream and flour in a small bowl. Add to skillet and cook, stirring constantly, 3 minutes or until slightly thickened. Add spinach, and cook 1 minute or until spinach wilts. Remove skillet from heat, and stir in lemon juice. Ladle mixture evenly into prepared ramekins.
Drop Parmesan Biscuit Topping (about 1/2 cup) evenly onto each pot pie. Place ramekins on a baking sheet, and bake 20 minutes or until browned.