1. In a large bowl with a hand mixer or the bowl of your stand mixer, combine the butter and sugar until smooth. Add the eggs and beat at medium speed until completely incorporated. Add the vanilla. In a medium bowl, whisk together the flour and baking powder. Add the flour mixture to the butter/egg mixture and stir just until the flour is completely incorporated. Remove the dough to a bowl. Cover with plastic wrap and refrigerate for at least 6 hours or up to 24 hours.
2. Preheat oven to 450° F. and butter a cast-iron skillet or high-sided baking dish.
3. In a medium saucepan, bring the maple syrup and heavy cream to a boil. Turn off heat, add a pinch of salt and set aside to cool.
4. Butter your skillet. Spoon the dough into the bottom of the skillet or baking pan and press down to level and cover the bottom. (alternately, you can divide the dough among 5 or 6 ramekins). Place your skillet, pan or ramekins on a baking sheet (*don't skip this part or you'll potentially be cleaning your oven later!). Pour the maple/cream sauce over the dough being sure not to fill the pan no more that about 2/3 full (the cake will rise and you'll be pushing the limits of the edges here. You may not be able to add every bit of it). Bake for 20-25 minutes or until the puddings are golden brown and a tester inserted into the center of each cake comes out clean. Let cool for 5 minutes, serve warm with vanilla ice cream, creme fraiche or even sour cream.