Preheat oven to 220ºC . Spray a baking sheet with vegetable pan spray. Wipe mushrooms clean and gently remove stems; reserve for another purpose. Put caps on baking sheet.
Put basil, olive oil, pine nuts, parmesan and garlic in food processor; process until finely chopped, scraping down sides of bowl once. Add stock through the feed tube and process until smooth. Add ricotta and process until mixed.
Divide mixture evenly among mushroom caps. Bake for 10 to 15 minutes or until hot.
Nutritional Information Per Serving (4 mushrooms):Calories: 68, Fat: 5 g, Carbohydrate: 4 g, Fiber: 1 g,Protein: 3 g, Sodium: 62 mg, Cholesterol: 4 mgDiabetic Exchanges: 1 Vegetable, -20ºC at