Brownie layer: Put an oven rack in the center of the oven. Preheat the oven to 350 degrees F. Spray an 8 by 8-inch glass baking pan with vegetable oil cooking spray. Line the pan with parchment paper, allowing 2 inches of paper to overhang the sides. Set aside. Spray the parchment paper with vegetable oil cooking spray.
In a large bowl mix together the water, oil and egg. Add the brownie mix and stir until blended. Stir in the chocolate chips and candy bar pieces. Transfer the batter to the prepared baking pan. Bake until a toothpick inserted into the center of the brownies comes out with a few moist crumbs attached, about 20 to 25 minutes. Remove the pan from the oven and cool the brownie layer completely in the pan, about 1 1/2 hours.
Ice cream layer: Using a spatula, spread the softened ice cream on top of the brownie layer and freeze until firm, about 4 hours or overnight.
Chocolate layer: In a small saucepan, heat the cream over medium-low heat until hot but not boiling. Remove the pan from the heat and add the chocolate chips. Stir until the chocolate has melted and the mixture is smooth. Using a spatula, spread the chocolate mixture over the ice cream layer. Freeze for at least 1 hour or until ready to serve.
Sauce: Put the strawberries, sugar and lemon juice in a blender and blend until smooth.
To serve: Remove the layers from the pan and peel away the parchment paper. Cut the layers into squares and drizzle with the strawberry sauce.
For a smoother sauce, strain the sauce through a sieve and discard the seeds.