Vegan Hot-Fudge-on-the-Bottom Cake

For the cake:
1 cup flour
¾ cup sugar
2 tablespoons unsweetened cocoa powder
2 teaspoons baking powder
½ teaspoon salt
½ cup almond milk
3 tablespoons canola oil
1 teaspoon vanilla extract

For the fudge:
½ cup brown sugar
½ cup sugar
¼ cup unsweetened cocoa powder
1-½ cups boiling water