Preheat the oven to 350° F. Grease a 9x13-inch pan.
Make the Cake:
In a mixing bowl, whisk together gluten free flour blend, salt, sugar, and baking powder.
Add the milk, eggs, and vanilla and beat until combined.
Beat in the melted butter until combined.
Transfer the cake batter to the prepared pan.
Make the Cinnamon/Sugar Layer:
In a separate bowl, beat together the cinnamon/sugar ingredients until combined.
Drop tablespoons of the cinnamon mixture over the cake batter. Using a table knife, draw lines through the batter, vertically and then horizontally, to create a swirled design.
Bake for 28-32 minutes until a toothpick inserted in the cake comes out clean.
Make the Glaze:
Whisk together the glaze ingredients until smooth.
Drizzle the glaze over the warm cake.
Notes
Generously grease the bottom and sides of the pan. This will ensure none of the tasty cake is left behind in the pan.