Melt the chocolate and butter in a glass bowl in the microwave. Add the sweetener, vanilla, flours, and eggs and stir until smooth.
Line a loaf pan with parchment paper and spray with cooking spray. Spread the brownie batter on top. Bake for 25 minutes. Cool completely.
You can either make the brownie base a day or two ahead or make it the same day as the rest of the cake. Just make sure to chill it for at least an hour in the refrigerator. It should be very cold before proceeding.
To make the ice cream combine all the ingredients in a blender and blend until smooth. Pour into an ice cream machine and churn according to the manufacturer's instructions.
When the ice cream finishes churning spread it on top of the chilled brownies. Freeze for at least one hour before adding the ganache.
To make the ganache microwave the chocolate and heavy cream at 30 second intervals until the chocolate is melted. Stir in the sweetener. Cool to room temperature. Spread on top of the frozen ice cream.
Let this sit out for 20 minutes before slicing. Simply lift the ice cream out of the pan by the parchment. Slice it on a cutting board with a sharp knife. Enjoy!