1. Preheat the oven to 180 degrees Celsius (350 degrees Fahrenheit). Grease a 20×30-centimeter (seven-by-11-inch) baking tin.
2. Place the three cups of flour, salt, sugar, baking powder, milk, eggs, and vanilla extract in the bowl of a mixer and mix. Once well combined, add the melted butter and pour into the prepared baking tin.
3. To make the topping, cream the butter, sugar, flour and cinnamon in a bowl until well combined. Drop evenly over the batter in the baking tin, then use a knife to marble through the cake batter. Bake for 35–40 minutes, or until a toothpick inserted into the middle comes out nearly clean.
4. For the glaze, mix the icing sugar, milk and vanilla together with a whisk in a medium-size bowl. Drizzle evenly over the still-warm cake and serve warm or at room temperature.