1 Preheat oven and prepare pan: Preheat an oven to 350°F. Spray a 9 x 13-inch baking pan lightly with cooking oil.
Line the pan with parchment paper, making sure about 1-inch of paper overhangs the long side of the pan. You will use the overhang to lift the bars out of the pan later.
2 Cream the butter, sugar, and spices: In the bowl of a stand mixer fitted with the paddle attachment, place the butter, brown sugar, vanilla extract, ginger, cinnamon, nutmeg, cloves, salt, and baking soda. With the mixer on medium-high, cream the ingredients together until the mixture forms a paste and clings to the side of the bowl, about 2 minutes.
3 Scrape, add molasses and egg, and mix: Use a rubber spatula to scrape down the side of the bowl and add the molasses and egg. Mix until incorporated, about 30 seconds on medium speed.
4 Scrape down the bowl: Use a rubber spatula to scrape down the…