Prepare a batch of same-day focaccia dough following recipe instructions up until tipping into tray
While dough is proofing, make the cinnamon sugar butter filling by mixing browned butter with brown sugar, cinnamon and vanilla extract
Line parchment on 9x13 inch tray with 2 tablespoons melted salted butter
Transfer dough to tray and gently stretch to edges
Mix ⅓ of diced apples with half of cinnamon filling, spread over dough and fold up
Flip dough over and cover to finish proofing at room temperature for 1-1.5 hours
Preheat oven to 215C/420F with rack in lowest position
Warm cinnamon sugar butter to drizzling consistency, mix with remaining ⅔ diced apples, spread over dough and dimple in
Bake for 23-25 minutes
While baking, whisk glaze ingredients: powdered sugar, milk, vanilla extract and cinnamon
Drizzle glaze over focaccia once out of oven, brush on top, sides and bottom
Transfer to cooling rack for glaze to harden for about 15 minutes
