Begin the cake recipe by preheating the oven to 350 degrees F. and lightly spraying an 8x8-inch square baking pan with cooking spray or line it with parchment paper. Set aside.
In a small bowl, whisk together 1 ½ cups all-purpose flour, 2 teaspoons baking powder, and ⅛ teaspoon kosher salt.
In a separate large bowl, use an electric mixer at medium speed to combine the ½ cup granulated sugar, ¾ cup milk, 1 large egg, 4 tablespoons melted butter, and 1 teaspoon vanilla extract.
Add the dry ingredients and continue mixing until combined. Pour the cake batter into the prepared square baking pan. Then set it aside while you mix the ingredients for the cinnamon swirl layer.
In a small bowl, use a whisk to combine the ½ cup softened butter, 1 tablespoon all-purpose flour, ½ tablespoon ground cinnamon and ½ cup brown sugar. Pour the mixture evenly on top of the cake mixture to form the cinnamon sugar layer.
Place into the oven and bake for 30 to 40 minutes or until a cake tester comes out clean.
Carefully remove the warm cake from the oven and allow it to cool while preparing the vanilla glaze topping. In a small bowl, whisk together the 1 cup powdered sugar, 2 tablespoons whole milk, and ½ teaspoon vanilla extract until combined.
Drizzle the glaze evenly over the cake while it is still warm and spread it evenly over the top with a knife. Allow the cake to continue to cool in the baking pan on a wire rack before cutting to serve. Enjoy!
Notes
To create the cinnamon sugar mixture, feel free to use light brown sugar or dark brown sugar. Both will work.
Top the cinnamon sugar mixture with chopped pecans or walnuts to add another layer of nutty and slightly sweet flavor.
Use a fork to poke holes in the top of the warm cake before adding the glaze to ensure that it seeps down into the rest of the cake.
After pouring the glaze on top of the warm cake, you may notice that it seeps in and forms holes on the top, this is perfectly fine.