Preheat the oven to 375°F. Line an 8x8 baking dish with parchment paper so the paper overlaps the sides a little. Brush the top of the parchment paper evenly with the peanut oil.
Add the dates and water to a food processor and blend until smooth. Scrape the pureed dates into a large mixing bowl.
Melt the chocolate in the microwave stirring every 30 seconds until completely melted or in a heatproof bowl over a saucepan of simmering water stirring often.
Add the melted chocolate and softened butter into the bowl with the dates and stir to combine. Whisk in the eggs until well combined. Add the cocoa powder and stir until well combined.
Pour the batter into the lined baking dish and use a rubber spatlua to spread the batter out evenly. Bake in the preheated oven for 25 minutes or until cake has an internal temperature of 200°F.
Invert the cake onto a cooling rack and remove the parchment paper. Allow the cake to cool at room temperature for 30 minutes then refrigerate for at least 30 more minutes before frosting.
FROSTING AND FINISHING:
Add the dates and water to a food processor and blend until smooth.
Melt the chocolate in the microwave stirring every 30 seconds until completely melted or in a heatproof bowl over a saucepan of simmering water stirring often.
Add the melted chocolate, heavy cream, and vanilla into the food processor with the dates and pulse a few times until well mixed and thickened.
Spread frosting on your chilled cake then refrigerate for at least 1 hour before serving.
Cut the cake from opposite corners then through the center of each side to make 8 nice size triangle slices of cake.