For the cake, preheat oven to 350F. Grease two 9-inch cake pans, lining the bottom with parchment paper.
In mixer, blend 3 cups of the flour, sugar, salt, baking powder, milk, eggs, vanilla and ¼ cup melted butter. Divide batter evenly between cake pans.
In another mixing bowl, beat ¾ cup butter with brown sugar, 2 Tbsp flour, and cinnamon. Continue to beat until fully blended and fluffy (about 3 minutes). Using two tablespoons, drop butter mixture onto cake batter. Use a knife to swirl.
Bake cakes for about 25-30 minutes. Remove from oven and cool in pans 10 minutes. Flip cakes out onto serving plates.
For icing, whisk the powdered sugar with ¼ cup milk and 1 tsp vanilla extract. Drizzle over warmed cakes. Enjoy!
