Preheat oven to 350 degrees Fahrenheit.

In a mixing bowl, combine flour, white sugar, cocoa (first amount), baking powder, and salt.

Add milk and canola oil to the dry ingredients.

Mix together with a spoon until just combined.

Scrape the batter into an 8-inch casserole dish that is fairly deep.

In the same bowl, mix brown sugar and cocoa (second amount) together.

Add hot water (not boiling) to the sugar and cocoa mixture.

Stir to dissolve the sugar.

Pour the hot water mixture over the batter in the casserole dish, but DO NOT stir.

Bake, uncovered, for 40 minutes.

The batter should have risen above the sauce and be firm to the touch when done.

Serve warm with vanilla ice cream or whipped topping.