My adaptation of this recipe:

http://www.bettycrocker.com/recipes/snickerdoodle-bars/e2fc9...

found courtesy of this post on the recipes board:

http://boards.fool.com/snickerdoodle-bars-29664864.aspx

GF Snickerdoodle Cake

2 1/3 cups Better Batter gluten-free all-purpose flour*
1 1/2 teaspoons baking powder
1/2 teaspoon salt
3/4 cup butter or margarine, softened
1 1/4 cups granulated sugar
1/2 cup packed brown sugar
3 eggs
1 teaspoon vanilla
1 c. milk

Cinnamon-Sugar Filling
4 TB granulated sugar
2 tsp cinnamon

Heat oven to 350° F. Spray or grease bottom only of a 13x9-inch baking pan with cooking spray. In small bowl, combine flour, baking powder, and salt; set aside.

In large bowl, beat butter with electric mixer on high speed until creamy. Beat in sugars. Gradually beat in eggs, vanilla, and milk into sugar mixture until combined. On low speed, beat in dry ingredients until combined.

Spoon half the batter into pan; spread evenly. Sprinkle half the cinnamon-sugar mixture evenly over batter.

Spread remaining batter evenly over cinnamon-sugar mixture. Top batter with remaining cinnamon sugar.

Bake 20 to 25 minutes or until golden brown and top springs back when lightly touched.

*or use gluten-free flour blend w/ 1/2 tsp. xanthan gum or 3/4 tsp. guar gum per cup of gluten-free flour