You can use regular all purpose flour cup for cup, just don't put in the xanthum gum. You can also use any kind of milk you like cup for cup.

A buttery and tender cake topped with a spiced crumb topping is the perfect accompaniment for a cup of coffee.#GlobalApron

Used to be on the box. Includes the topping already doubled.

My grandmother, Florence Knight

I found a coffee cake recipe on another site and the exact same one with an easier execution here from our friend @Xrusa98. Of course, I made Xrusa's version with a small change and then made the buttercream from the other site.

This is a cake that a friend made for me when I lived in a dormitory. She used Bisquick, so I experimented using Japanese pancake mix to achieve a similar taste.You can make a thicker topping by increasing the amounts of butter and sugar. I only used a small amount for the cake in the photo, so the topping is quite light. Feel free to adjust the amounts to your taste. Recipe by Tsukushigumi

Very easy to make and tastes sooo good!