In a large bowl, combine the warm milk, sugar, and instant yeast. Let it sit for 5-10 minutes until it becomes frothy.

Add 2 ½ cups of flour, salt, melted butter, egg, and vanilla extract to the yeast mixture. Mix until a sticky dough forms, then knead it on a lightly floured surface until smooth and elastic, about 5-7 minutes.

Place your dough in a greased bowl, cover it, and let it rise in a warm place for about 1 hour, or until it doubles in size.

In a separate bowl, mix 1 ½ cups of flour, ¾ cup of sugar, and 1 tsp of cinnamon. Add the cold, cubed butter and work it into the dry ingredients until crumbly.

Once the dough has risen, roll it out on a floured surface to fit into a greased baking pan, about 1 inch thick.

Spread the dough evenly into the pan and sprinkle the crumb mixture generously on top.

Preheat your oven to 350°F (175°C) and bake for 25-30 minutes or until golden brown.