Preheat oven to 450 degrees. Prepare baking sheet by lining with parchment paper or drizzling olive oil on pan.
Thaw bread dough.
Roll dough into an oval shape and place on prepared baking sheet. Poke fingers down into dough making dimples in the dough, brush with melted butter.
Place dough in preheated oven for 5 minutes.
Remove crust from oven. Spread caramelized onions over flatbread, place apple slices evenly over onions, sprinkle with cheddar cheese.
Bake in 450 degree oven for 12-15 minutes or until cheese is bubbling and starting to brown. Remove and drizzle a teaspoon of olive oil over flatbread and sprinkle with chopped walnuts and rosemary. Cut into small pieces and serve!