Preheat oven to 350°F (177°C) and grease and flour four 6-inch cake pans and line the bases with baking parchment.

Warm up the milk in a small saucepan and add to the bowl of your stand mixer fitted with the paddle attachment. Add molasses and stir until combined. Let sit for a short moment to cool down.

In a medium bowl, combine the flour, baking powder, baking soda, sugar, salt, and spices. Set aside.

Add the vegetable oil, buttermilk, eggs, rum and vanilla to the molasses and milk mixture and mix well at low speed until combined. Add the dry ingredients and whisk into a smooth batter. Do not overmix.

Divide the batter between the prepared baking pans and bake for 25-30 mins until a skewer inserted into the center of the cakes comes out mostly clean.

Place cakes on a wire rack to cool for 10mins, then turn out onto the wire rack, peel off the parchment and leave to cool completely.

To make the Baileys cream cheese frosting: Beat room temperature butter and room temperature cream cheese until fluffy for about 2 minutes. Add confectioners' sugar one cup at a time. Add cinnamon and beat until fluffy for about 3 minutes. Then beat in the baileys.

To assemble the cake: Transfer 1/3 of the frosting to another bowl and set aside. Use the remaining frosting to stack the cake layers. If your layers are uneven, level them with a long bladed knife. Use other 1/3 of frosting to apply a thin coat of frosting all over the cake and use a bench scraper to smooth the sides. Chill the cake in the fridge before serving, cream cheese frosting tends to get soft when not chilled.