Grease a 9 x 13 baking pan with lots of butter and line with parchment paper that has also been greased. Preheat oven to 350 degrees.

For the crumb top: pulse dry mix in food processor. Add butter and shortening and pulse until crumbs the size of peas. Set aside.

For the filling combine the brown sugar and cinnamon in a small bowl, set aside.

For the cake batter: In a medium sized bowl, sift baking mix, baking powder, salt and pudding mix three times (or use a triple sifter once). Set aside.

Cut butter into 1 inch pieces and put them in a large bowl. Soften with a mixer on low speed. Increase the speed to medium high and cream until light in color, about 1 ½ to 2 minutes. While still mixing, add sugar 1 tablespoon at a time, taking about 4 minutes to blend it well.

Add egg. Mix. Scrape bowl.

Add sour cream. Mix. Scrape bowl.

Add vanilla.

With the mixer on low, add about half of the dry ingredients. When incorporated, add half of the rice milk. Then half of what is remaining of the dry, then the rest of the rice milk, ending with the remaining dry. In other words, alternate between the dry and wet, starting and ending with the dry mix. Mix JUST until incorporated after each addition. Scrape the sides of the bowl as necessary.

Pour half of the batter into your prepared pan. Sprinkle the cinnamon sugar mixture evenly on top. Add remaining cake batter. Top the cake with crumb mixture.

Bake for 35 to 40 minutes.

Once cooled, top with powdered sugar.