Preheat oven to 350° F. Spray the bottom of an 9x9 baking pan with cooking spray and line the bottom with parchment paper, spray the parchment paper with cooking spray.
In a large bowl whisk together the dry ingredients.
Whisk together the molasses and hot water until combined. Set aside.
In the bowl of an electric mixer with the paddle attachment or with a handheld mixer, beat the butter for one minute on high speed. Add in the Greek yogurt and brown sugar and beat until well until combined, about 3 minutes. Scrape down the sides of the bowl as needed.
Add in the egg and vanilla and beat until combined.
With the mixer on low speed, add the dry ingredients in three additions alternating with the molasses mixture. Begin and end with the dry ingredients. Avoid over-mixing the batter.
Pour the cake batter into the prepared baking pan and bake for 30-35 minutes or until a toothpick inserted in the center comes out with a few crumbs attached. Cool the cake completely on a wire cooling rack before frosting it.