Cake: In a large bowl, with an electric mixer, beat butter and sugar until light. Add eggs and vanilla and mix. In another bowl, mix flour and baking powder. Add dry ingredients to the butter mixture, alternating with the milk, and mix well. Pour the batter in a greased 13' x 9' oven glass dish.
Sauce: In a large saucepan, bring to boil the syrup, brown sugar, heavy cream and butter while stirring. Reduce the heat and let simmer for 2 minutes or until the sauce has slightly reduced. Pour slowly the boiling sauce on the batter.
Cook in a preheated oven of 325 F for about 35 minutes or until the top of the pudding is golden and a toothpick inserted in the middle comes out clean. Serve warm or at room temperature.