Spray a 9 x 13" cake pan with non-stick spray, line the bottom with parchment paper, and spray the parchment paper with more non-stick spray. Preheat your oven to 350°F.
Make the cake batter: Whisk the flour, baking powder, baking soda, salt, and cinnamon in a medium bowl. In a larger bowl, whisk the melted butter, granulated sugar, brown sugar, room temperature eggs, vanilla extract, whole milk, and sour cream until smooth. Add the dry ingredients and whisk until smooth.
Prepare the filling: In a small bowl, whisk the flour, brown sugar, and cinnamon together until evenly combined.
Pour just enough of the cake batter into the pan to cover the bottom in an even layer. Sprinkle the filling on top, then cover with the rest of the cake batter. Use a spatula to spread it out evenly.
Make the streusel topping: Whisk the flour, brown sugar, and cinnamon in a medium bowl. Add the softened butter and use a fork or a pastry blender to mix it in until the mixture is thick and crumbly. Sprinkle the streusel topping all over the top of the cake batter in the pan.
Bake for 35 minutes. A toothpick inserted into the center will come out clean.
Make the vanilla glaze: Whisk the powdered sugar, milk, vanilla extract, and salt until smooth. Drizzle the glaze over the top of the cake.