I want to make a layer cake (3 layers) that has both oil and butter.  My goal is super moist and I prefer to dense to fluffy.  

I know the pudding mix, sour cream thing is always recommended, however I have tried it and I think the flavor of the pudding mix is really chemically.  I had a vanilla cake made with oil and it had just the right texture, but not enough flavor.  So I want to try a cake that is an oil/butter blend.  

So I'm thinking of using melted butter rather than creaming and using half oil where it calls for all butter.  What do you think, does this sound right, or do I need to add anything else?

Also does buttermilk make a cake more dense than whole milk?  Or maybe should I add some sour cream?

Any recipes or thoughts would be much appreciated!

I wouldn’t melt your butter, but cream it with your sugar and eggs. Better structure that way. I’ve done a combo oil/butter cake as I don’t like a all butter cake. Personally, I found all butter cake very greasy. I’ve never done the “pudding” thing. I’ve always added either sour cream/yogurt/mayo to make a dense cake. Buttermilk doesn’t make a cake dense, it adds a depth of flavour.