Preheat your oven to 350°F. Lightly butter a small pan (like a mini dutch oven or a 5" cake pan).

In a bowl, mix oil, yogurt, and 2 tablespoons of boiling water until smooth. Add sugar and mix well.

Sift in flour, cocoa powder, baking powder, baking soda, and salt. Gently fold everything together until just combined.

Pour this cake batter into the buttered pan.

In another small bowl, mix granulated sugar, brown sugar, and cocoa powder until smooth. Sprinkle this over the cake batter.

Carefully pour ⅓ cup of boiling water over the sugar and cocoa mixture on top of the batter.

Place the pan in the preheated oven. Bake for about 20 minutes until the top of the cake looks done. It's better to underbake slightly so there's plenty of fudge sauce at the bottom.

Serve the cake warm straight from the pan. You can add cold whipped cream or ice cream on top if you like.