In small bowl, crush 1 cup of the strawberries. In 2-quart saucepan, mix sugar and cornstarch. Stir in crushed strawberries and 1/3 cup water. Cook over medium heat, stirring constantly, until mixture boils and thickens. Stir in food colour. Cool 10 minutes. Gently stir in remaining 3 cups strawberries. Spoon topping over filling. Refrigerate 1 hour or until set; serve within 4 hours. Store covered in refrigerator.