Ok, to start with, IF you do use Sour Milk in this recipe, DON'T Mix it with the Soda.  The acid in the Sour Milk {also known as Buttermilk} neutralizes the Soda, killing the only leavener in the recipe.  This isn't necissarily BAD, but will create a very heavy, very dense unleavened cake--much like a heavy N.E. maritime "biscuit".  If you use regular milk, the soda should be preserved enough to leaven the dough somewhat.

Secondly, you can skip the "butter flavouring" if you just use butter flavoured shortening.  Though not exactly "natural", neither is butter flavouring.  I do know of a couple organic, non-trans-fat versions.  If you are that worried, use these and save this step.

Thirdly, if you chose to make this, just go for the Creaming Method.  I'm not saying this is necissarily a cake, but seems more like a streudel--which judging by the topping makes it a pretty standard streudel.  Again, this isn't a flaw, but just something you should be aware of; this ISN'T a traditional "bread".

Finally, this doesn't sound like a home-developed recipe; at least not in the form it is in now.  The ingredients, pan size, and format seem more like a keifed {or adapted} recipe from a commercial baker.  I'm not trying to nay-say the recipe, I'm simply stating that it sounds like it came down through a few too many lines before reaching the page.

My opinion?  It's possible to fix this, but you probably want to know what you're doing. Just promise you'll be careful with this one...?