Start by heating your oven to 350°F (175°C). Take an 8×8-inch baking pan, grease it well, and then lightly dust it with cocoa powder so the cake doesn’t stick.

Next, melt the chocolate and butter together. You can do this gently in a saucepan over low heat or in the microwave in short 20-second bursts, stirring each time. Once smooth, set it aside to cool just a little.

While that’s cooling, combine the dry ingredients in a large bowl. Whisk together the flour, cocoa powder, baking powder, and coffee granules until everything is evenly mixed.

In a separate bowl, mix the wet ingredients. Beat the eggs with the sugar, oil, and vanilla extract until smooth. Gradually stir in the melted chocolate and butter so the mixture becomes uniform.

Now bring the wet and dry parts together. Slowly fold the dry ingredients into the wet mixture. Then, carefully pour in the boiling water while stirring until the batter is smooth. Don’t worry that it looks thin that’s exactly how it should be.

Pour the batter into the prepared pan and bake it in the oven for 30–35 minutes. Test for doneness by inserting a toothpick in the center; if it comes out clean, the cake is ready. Let it cool slightly before serving.

While the cake is cooling, make the whipped cream. Use a cold bowl to whip the heavy cream with powdered sugar and vanilla until soft peaks form. Keep it chilled until you’re ready to serve.

For the hot fudge sauce, combine the chocolate, sweetened condensed milk, corn syrup, water, and a pinch of salt in a saucepan over low heat. Stir constantly until the sauce is smooth and glossy. Take it off the heat and mix in the vanilla extract. Serve the warm fudge over slices of cake with a dollop of whipped cream.