Preheat oven to 350℉. Butter 3 x 6-inch round cake pans. Line with parchment paper. Set aside.
In a medium bowl, whisk together flour, cinnamon, ginger, nutmeg, baking soda, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter and brown sugar* until smooth. Scrape down bowl as needed to ensure thorough mixing.
Add eggs and molasses and mix until combined.
Add 1/3 of dry ingredients and mix on low speed. With the mixer running, slowly add 1/2 of milk. Repeat with another 1/3 of dry ingredients and remaining milk. End with last 1/3 of dry ingredients. Mix until just combined. Scrape down sides of bowl as needed.
Divide batter among prepared cake pans. Spread into an even layer. Bake for 30-35 minutes, until toothpick inserted in center of cake comes out clean. Rotate halfway thru baking.
Remove cakes from pan and allow to cool to room temperature on a wire rack.