• Preheat oven to 325 degrees F. Grease and flour two 8x4 inch (4-cup capacity) loaf pans or one 9x5 inch loaf pan.
• Sift together the flour, baking powder and salt. Stir in the pudding mix.
• In the bowl of a stand mixer, beat butter, coconut oil and sugar until light and creamy. Add each egg one by one, beating on medium speed and beating for 30 seconds after each egg is added. By hand, add the flour mixture alternately with the milk. Beat on low until smooth, then beat in rum and vanilla.
• Pour into the pans (or pan) and set on a rimmed baking sheet. Run a knife through the batter to help release extra air. For two smaller cakes, bake for about 1 hour at 325 degrees F. For a 9x5 inch loaf pan, bake for about 1 hours and 15 minutes (75 minutes) but check at 1 hour. The cake should crack on top.
• The next step is to glaze it, which you will do while the cake is still warm. So right after you take the cake from the oven, let it sit for 10 minutes and start making the glaze.

Glaze

• Begin melting the butter over medium heat in a small saucepan. Add the water and the sugar and continue heating until butter is melted, then add the rum. Bring to a boil (it will look foamy). Remove from heat. Allow foaming to subside and stir in the vanilla extract.
• After about 10 minutes, you can remove the cake from the pan or just leave it in there. I usually just leave it in there so that I can loosen it and remove it once it's cool and more stable. With a metal skewer, poke holes all over the warm cake being careful not to go all the way through. Gradually spoon the warm glaze over the cake, giving it time to sink down into the holes and soak in.
• Allow the cake to cool slightly, then cover with foil and leave it alone for several hours or overnight.
• Now here's the hard part. Leave the cake(s) alone until the next day! Keep covered in foil or put in zipper bags and serve on day 2.