Preheat your oven to 350°F (175°C) and line a small square baking dish with parchment paper.
In a bowl, sift together flour, cocoa powder, baking soda, and salt.
In another bowl, whisk oil, yogurt, sugar, and vanilla until smooth. Mix in dry ingredients.
Add hot water and mix until the batter is lump-free.
Pour into the pan and bake for 20–25 minutes. Let cool completely.
In a mixing bowl, whip heavy cream until stiff peaks form. Fold in condensed milk and vanilla extract.
Crumble the cooled cake and layer it into a container, alternating with scoops of the ice cream base.
For the ganache: heat cream until simmering, pour over chocolate, and stir until smooth.
Pour ganache over the layered cake and ice cream. Freeze for at least 6 hours or overnight before serving.