In a saucepan over medium heat, add four cups of raspberries, and one-quarter cup of granulated sugar. Stir until the raspberries have broken down, and the sugar has dissolved.
Remove the saucepan from the heat and stir in one teaspoon of lemon juice and one tablespoon of vanilla extract. Set the mixture aside to cool and prepare the topping.
Preheat the oven to 350°F and lightly grease a baking dish.
In a mixing bowl, sift one and one-quarter cups of Bisquick, one-third cup of cocoa powder, and one-quarter cup of sugar.
With an electric mixer, beat in one-half cup of milk, and one-half cup of softened butter until the mixture is well combined.
Fold in one-half cup of chocolate chips.
Pour the cooled raspberry mixture into the prepared baking dish.
Spoon the topping evenly over the bottom mixture.
Bake for thirty minutes, or until the top is golden brown.
Serve with ice cream or whipped cream and enjoy.