Preheat the oven to 350 degrees F. Grease and flour a 9- by 13-inch baking pan.
With a hand-mixer or stand mixer, beat granulated sugar and Crisco until combined.
Add eggs and continue to mix.
Add flour, milk, and vanilla and beat for 1-2 minutes until fully combined.
Spread half of the batter into the prepared pan.
Combine brown sugar and cinnamon in a small bowl and mix.
Sprinkle cinnamon-brown-sugar mixture over the batter in the pan, then spread the remaining cake batter on top. Swirl with a knife.
Bake for 30-45 minutes, until a toothpick inserted into the cake’s center comes out clean.
While the cake cools, combine milk, butter, sugar, and vanilla in a saucepan and heat until a gooey icing forms.
Poke holes in the cake with a fork and pour the warm icing over top.
