Preheat the oven to 350 degrees. In a bowl, whisk together the flour, baking powder, cinnamon, salt and baking soda.
Using a standing mixer, beat the butter at medium-high speed until creamy; gradually add the brown and granulated sugars and mix well. Add the eggs one at a time, beating well and scraping down the sides of the bowl after each addition. On low speed, beat in the flour mixture, one-third at a time, alternating with the milk and ending with the dry ingredients. Mix in the molasses on medium-low speed. Mix in the whiskey until smooth, about 30 seconds.
Pour the batter into a greased, parchment-paper-lined 10-inch cake pan and bake for 30 to 35 minutes. Let cool.
Serve the cake with vanilla ice cream, chocolate sauce and candied pecans, if using.