Preheat your oven to 350°F (175°C).
Cream together 4 tablespoons of softened butter and 1 cup of sugar until light and fluffy. Add in the egg and mix well.
In a separate bowl, combine the warm milk and baking soda. Slowly add this mixture to the butter and sugar mixture.
Sift together 2 cups of flour. Gradually add the flour to the wet ingredients, mixing until just combined.
Pour the batter into a greased 9x13 inch baking dish and bake for 25-30 minutes, or until a toothpick inserted comes out clean.
Allow the cake to cool completely on a cooling rack.
In a mixing bowl, beat together the softened cream cheese, 2 sticks of softened butter, and the can of sweetened condensed milk until smooth and creamy.
Spread the cream cheese mixture evenly over the cooled cake. If using, crush graham crackers and sprinkle over the cream cheese layer.
Spread the thawed Cool Whip evenly over the cream cheese layer.
Refrigerate the cake for at least 2 hours before serving.
