Cinnamon Streusel Breakfast Cake

OK, so this is a coffee cake.  But the Domestic Sergeant and I don't drink coffee.  And this is something I can feed my girls in the morning or pack in their lunches.  It's an old-fashioned style goodie, and like the best vintage recipes, it's eminently flexible.

Cinnamon Streusel Breakfast Cake

Streusel Topping

1/4 c. gluten-free oats
1/4 c. gluten-free oat flour (amaranth, millet, or quinoa would also work)
1/4 c. brown sugar
1/2 tsp. cinnamon
1/4 c. butter, softened

Cinnamon Filling

1/3 c. brown sugar
1/2 tsp. cinnamon
2 Tbsp butter (salted)

Cake

2 1/2 c. Fancy Flour Blend OR
1/2 c. millet flour
3/4 c. white rice flour
1/4 c. + 2 Tbsp sweet rice flour
3/4 c. tapioca starch
2 Tbsp potato starch
2 tsp baking powder
1/2 tsp xanthan gum
1/2 tsp salt
14 Tbsp. butter, softened
3/4 c. sugar
1 egg + 1 egg white
1 5.3 oz Honey flavored Greek Yogurt
1 tsp. vanilla
3 Tbsp milk

Preheat oven to 350 degrees. Lightly spray a 9" baking pan with nonstick cooking spray.

In a small bowl, combine oats, 1/4 c. brown sugar, oat flour, and cinnamon. Mix to combine.

With a pastry blender, cut in 1/4 c. butter until mixture is crumbly.  Set aside.
In another small bowl, combine 1/3 c. brown sugar and cinnamon.  Work in 2 Tbsp of butter with a fork until thoroughly combined.  Set aside.

In the bowl of a stand mixer, cream butter and sugar.  Beat until light and fluffy.  Beat in egg and egg white.

Stir in yogurt, milk and vanilla.

Combine dry ingredients and add them to butter mixture. Beat for about two minutes, until smooth. Spoon 1/2 of mixture into pan and spread to cover bottom with a wet spoon. Top with cinnamon filling, then with remaining batter. Sprinkle streusel on top. Bake for 35-40 minutes, or until a toothpick inserted into center comes out clean.

Caramel icing

2 Tbsp butter (salted)
3 Tbsp brown sugar
3/4 c. powdered sugar
2-3 tsp. milk

In a small saucepan, melt butter and stir in brown sugar. Add powdered sugar and milk alternately until smooth. Drizzle over cake.

Now, this cake doesn't need the icing at all.  But icings of any kind are a sure-fire way to get The Empress of Cute to try something.  Leave it off it you like.
When fresh fruit is in season, you can change it up.  Omit the cinnamon filling and stir in 1 c. of fresh cherries or blueberries, and add 1/4 c. toasted almonds to the streusel.  Or leave off the streusel, and replace the filling with fresh raspberries, topping the cake with a sprinkling of coarse sugar.  Make it your own.
Or make my version....