Preheat oven to 500 F (260 C).
- Heat a sauté pan or skillet to medium-high heat.
- In the pan, combine apple, brown sugar, cinnamon, and butter. Cook until apples are soft, and the mixture is sticky. Set aside.
- In a small bowl, crumble together butter, brown sugar; and flour; mix until sandy in texture. Set aside.
- In a small bowl, combine milk and icing sugar together to make glaze. Set aside.
- Lightly butter an oven ready pan that is large enough for the pizza dough.
- Roll out pizza dough, place on pan, bake for five minutes.
- Remove pizza dough from oven. Place apple mixture onto the dough, then top with the crumble, leaving space on the edge for a crust to develop.
- Return to oven and bake for five more minutes or until the crumble begins to brown.
- Remove from oven, cool slightly, then drizzle with glaze.
- Cut and serve warm.