Preheat oven to 350°F. Spray a 9×13 glass baking pan with cooking spray. Set aside.

In an electric or stand mixer add the flour, salt, sugar, baking powder, milk, eggs, and vanilla. Once combined well , slowly stir in the melted butter. Pour into the prepared 9×13 baking pan.

For topping, In a large bowl mix the 2 sticks of butter, brown sugar, flour and cinnamon together until well combined and creamy. Drop evenly over the batter by the tablespoonfuls and use a knife to marble/swirl through the cake.

Bake at 350 for 35-40 minutes or when a toothpick inserted near the center comes out nearly clean.

FOR GLAZE: In a medium bowl, mix the powdered sugar, milk and vanilla together with a whisk. Drizzle evenly over the warm cake. Serve warm or at room temperature.