Preheat your oven to 325 degrees F. Spray three 8-inch or four 6-inch pans with nonstick spray, line the bottoms with parchment and spray again. Set aside.
In a medium bowl, sift together the dry ingredients and set aside.
Place butter in the bowl of an electric mixer and beat on medium-high for 2 to 3 minutes.
Add in the brown sugar and cream together on medium speed for another minute.
On medium-low, gradually add in the eggs and molasses until incorporated.
With the mixer on low speed, alternately add the flour mixture and the buttermilk, starting and ending with the dry ingredients.
Once mixed, evenly divide all of the batter into the prepared pans (about 16 ounces in each 8-inch pan or 12 ounces in each 6-inch pan).
Bake 25 to 30 minutes, checking around 25 minutes. When you insert a toothpick into the center of the cake, a few moist crumbs should come out on it. Remember, the cake continues to bake for 5 minutes as it cools in the pans.
Cool on a wire rack before de-panning.