In a medium-sized saucepan, heat the apple cider over medium-high heat until boiling. Remove from heat and carefully stir in the baking soda. *Mixture will bubble up considerably so don't skimp on the saucepan size. Allow to cool while you prepare the rest of the batter. *You can also do in the microwave in a large bowl.
Preheat oven to 350°F. Butter or spray with cooking spray a 9x9 baking dish or a 10-inch top diameter cast iron skillet.
In a large bowl or bowl of a stand mixer, beat the butter and white sugar until light and fluffy. Add in the eggs, one at a time, beating well after each addition.
In a small bowl, combine the flour, baking powder and spices.
Add half the flour mixture to the butter/sugar mixture. Mix to combine. Add half the cider and stir in. Add the rest of the flour and the rest of the cider, stirring after each addition. Add the diced apples and chopped pecans and stir to combine.
Pour into prepared pan and place in preheated oven.
Bake for 30-35 minutes or until it tests doneness with a toothpick in the center. It should come out clean and the top should be browned.
Using a skewer, poke some holes all over the cake, then pour 1/2 of the toffee sauce over cake. Allow to stand a few minutes (to allow it to soak in), then pour the remaining toffee sauce over-top.
For the Toffee Sauce (prepare when the puddings are baking): Melt the butter in a small saucepan over medium heat. Add in the brown sugar. Stir and cook until the sugar is dissolved. Slowly pour in the cream (will bubble up!) and reduce heat and simmer until the sauce thickens. Remove from heat and stir in the vanilla. (Can be made ahead and re-warmed in the microwave before serving)
You can substitute unsweetened apple juice for the apple cider. Or mix 1/2 cup unsweetened applesauce with 1/2 cup hot water, then let cool before using.For a dessert for two (or 3), halve the recipe and bake up in a 6-inch skillet or smaller dish.Be sure to read the "Cook's Notes" in the original post, for more tips, options, substitutions and variations for this recipe!