Get your oven ready - Heat it to 350°F. Roll out your pie crust to fit a 12-inch pizza pan and fold the edges up a bit to make a little border.
Fix up the apples - Mix the white sugar, 3 tablespoons flour, and cinnamon in a bowl. Toss your diced apples in this mixture until they're all coated. Spread them evenly over your pie crust.
Make the crumb topping - In another bowl, mix together the flour, brown sugar, oats, cinnamon, and soft butter. I like to use my hands to squish it all together until it looks like wet sand with some bigger chunks. Sprinkle this all over the apples.
Bake it up - Pop it in the oven for 35-40 minutes. You'll know it's done when the apples are tender and the topping is golden brown.
Finish and serve - As soon as it comes out, drizzle that caramel sauce all over the top. Cut it into wedges like a pizza and serve with ice cream while it's still warm.