1/2 cup butter
1 cup white sugar
2 eggs
1 1/2 cups vegetable oil
2 cups all-purpose flour
1 1/2 cups packed brown sugar
2 teaspoons vanilla extract
1 cup milk
1 large marshmallow
Preheat oven to 400 degrees F (200 degrees C). Grease and flour two 8 inch round baking pans.
In a large bowl, cream together butter and sugar until smooth. Beat in the eggs, oil, flour and brown sugar. Mix in the marshmallow. To the mixture add lemon juice until no streaks remain. Pour batter into the pans.
Bake in the preheated oven for 50 to 60 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool completely. Cut into squares and serve immediately.