1-Preheat the oven to 350°F (175°C): Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking dish or line with parchment paper.
2-In a large bowl, whisk together flour,: In a large bowl, whisk together flour, sugar, baking powder, and salt. Add milk, eggs, vanilla, and melted butter. Stir until smooth but don’t overmix – just until everything is combined.
3-In a separate bowl, combine softened butter,: In a separate bowl, combine softened butter, brown sugar, cinnamon, and flour. Mix until creamy and spreadable.
4-Pour the cake batter evenly into the: Pour the cake batter evenly into the prepared baking dish. Drop spoonfuls of the cinnamon mixture over the batter. Use a butter knife to gently swirl it into the top – don’t mix it all the way through.
5-Bake for 35-40 minutes, or until a: Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean (a few moist crumbs are okay).
6-Beat together cream cheese, powdered sugar, milk,: Beat together cream cheese, powdered sugar, milk, vanilla, and a pinch of salt until smooth. Add a splash more milk if you prefer a thinner drizzle.
7-While the cake is still warm, pour: While the cake is still warm, pour the glaze over the top. Let it melt slightly into the swirls before slicing. Enjoy warm.