In a medium bowl, combine the granulated sugar, brown sugar, cinnamon, salt, and flour for the crumble topping.
Add the cold, cubed butter. Using a pastry blender, a fork, or even just your fingers, cut the butter into the dry ingredients until the mixture resembles coarse crumbs, like pea-sized bits or slightly smaller.
Pop the crumble mixture in the fridge for a few minutes while you prep the base.
Preheat your oven to 375°F (190°C).
Grab a baking sheet and line it with parchment paper.
Unroll the crescent roll dough. You can either leave it as one big rectangle (pinching the seams together really well) or separate it into the four rectangles and arrange them on the baking sheet, pinching seams to form one larger rectangle or rustic circle shape. Make sure those seams are sealed.
Take your prepared crumble out of the fridge.
Sprinkle it evenly over the surface of the crescent roll dough on your baking sheet, going right up to the edges.
Place the baking sheet in the preheated oven and bake for 10-14 minutes, or until the crescent roll base is golden brown and cooked through, and the crumble topping is golden and looks delightfully crispy. Keep an eye on it.
While the pizza is baking, whisk together the powdered sugar, softened butter, and vanilla extract in a small bowl.
Add the milk, starting with 1 tablespoon. Stir until it's smooth and drizzle-able. If it's too thick, add just a tiny splash more milk (like half a teaspoon at a time) until it reaches your desired consistency.
Once the pizza is out of the oven, let it cool on the baking sheet for just 5-10 minutes.
Then, drizzle the glaze generously all over the warm cinnamon-sugar pizza. You can use a spoon or even put the glaze in a small zip-top bag, snip off a corner, and pipe it on for fancy drizzles!
Slice it up like a pizza (a pizza cutter works great!) and serve warm. Enjoy the smiles!