For dough: Combine yeast, sugar, hot water, and warm milk in a mixing bowl. Stir till yeast dissolves. Add salt and oil.
Stir in one cup of the flour and mix well. Add enough remaining flour to make a soft dough. Knead a few times on a floured counter. Return to the bowl, cover, and let rest 15 minutes.
For filling: Melt butter in a skillet. Add remaining ingredients. Cook and stir over medium heat for 5 minutes.
Turn heat to low; cook and stir for 3-4 more minutes, or till apples are crisp tender.
For topping: Combine all ingredients in a small bowl. Mix with a fork till crumbly.
To assemble pizza: Pat dough onto an 8-9" circle on a lightly greased cookie sheet, making a rim around the edges. Arrange the apples evenly over the crust. Sprinkle the crumb topping over the apples.
Bake at 350° for 20-25 minutes or till crust is golden brown.