Preheat your oven to 350°F (180°C). Grease a 9x13-inch baking pan or a similar size.

In a large mixing bowl, whisk together the eggs, granulated sugar, and vegetable oil until smooth.

Pour in the warm milk and mix until fully combined.

In a separate bowl, sift together the all-purpose flour, cocoa powder, baking powder, and baking soda. Sifting prevents lumps and creates a lighter crumb.

Gradually add the dry ingredients to the wet mixture. Stir just until the batter is smooth and no dry streaks remain. Avoid overmixing, which can make the cake tough.

Pour the batter into the prepared pan and spread it evenly.

Bake for 45 to 50 minutes. A toothpick inserted into the center should come out clean or with a few moist crumbs.

Let the cake cool in the pan for about 10 minutes before adding the sauce. The cake should still be warm when you poke the holes.

In a medium saucepan, combine the sugar, cocoa powder, milk, and butter.

Cook over medium heat, whisking constantly, until the sugar and cocoa dissolve completely.

Bring the mixture to a gentle simmer. Continue stirring for 3 to 5 minutes, or until the sauce thickens slightly and coats the back of a spoon.

Remove from heat. The sauce will thicken a bit more as it cools, so do not overcook it.

In another saucepan, combine the sweetened condensed milk, heavy cream, and cocoa powder.

Cook over medium-low heat, stirring continuously. This prevents scorching and ensures a silky texture.

Once the mixture is creamy and thickened, about 5 to 7 minutes, add the milk chocolate bar broken into pieces.

Stir until the chocolate is completely melted and the topping is smooth.

Remove from heat and let it cool for 5 minutes. It should be pourable but not boiling hot.

While the cake is still warm, use the handle of a wooden spoon or a skewer to poke small holes across the entire surface. Space them about 1 inch apart.

Slowly pour the chocolate sauce over the cake. Let it seep into the holes and spread naturally. Use a spoon to guide the sauce if needed.

Allow the cake to absorb the sauce for 10 minutes.

Spread the chocolate fudge topping evenly over the top. Use an offset spatula for a smooth finish.

Let the cake cool completely at room temperature. The fudge topping will set into a soft, sliceable layer.

Slice, serve, and enjoy this incredibly chocolatey dessert.