Make the apple pie filling
In the morning, combine the diced apples, brown sugar, lemon juice, vanilla, cinnamon, nutmeg, ginger, salt, and butter in a medium saucepan over medium heat. Cover and cook, stirring occasionally, until the apples soften, about 8 to 10 minutes. Whisk the 8 g cornstarch with the 30 g water until completely smooth, pour it into the apples, and stir constantly for 1 to 2 minutes until thickened. Remove from the heat and keep the filling warm and pourable while you shape.
Prepare your pan
Grease a 9x13 inch baking pan generously with butter or cooking spray.
Prepare cinnamon sugar coating
In a shallow bowl or plate, whisk together granulated sugar, cornstarch, and cinnamon. Set aside for dipping.
Ball, Dip and Coat
Turn the risen dough out onto a lightly oiled surface. With oiled hands, pinch off a golf ball size piece of dough, dip it into the warm apple pie filling so all sides are coated and a few apple chunks come along with it, then immediately roll it in the cinnamon sugar until completely covered. Place it in the prepared pan and repeat with the remaining dough, arranging the balls so they touch.
Second rise
Cover loosely with plastic wrap or a damp towel and let rise for 1-2 hours at room temperature, or until puffy and the balls have grown together. They should jiggle slightly when you shake the pan.
Add remaining filling
After the second rise, pour or spoon any remaining apple pie filling over the top of the proofed focaccia.
Bake
Preheat oven to 425°F (220°C). Bake for 35-40 minutes, or until deep golden brown on top. If the top is browning too quickly (check around 25 minutes), tent with foil. The internal temperature should reach about 200-205°F. Cool in the pan for 10 minutes.
Make the Caramel Glaze (See notes section for alternative)
Make caramel
In a microwave safe bowl, combine the 67 g granulated sugar and 20 g water and do not stir. Microwave on high for 1 minute, then continue in 30 second intervals while watching closely, until the syrup turns a medium amber color, about 2½ to 3 minutes total. The sugar is extremely hot, so handle the bowl carefully.
Add cream and butter
Carefully stir in warmed heavy cream (it will bubble up dramatically!), butter, vanilla, and salt. The mixture will seize up at first but keep stirring. Let cool for 5-10 minutes until just warm to the touch.
Finish glaze
Whisk in powdered sugar until smooth. The glaze should be pourable but have some body to it.
Glaze
Drizzle the caramel glaze generously over the warm focaccia. Make sure every piece gets covered.
Let the glaze set for a few minutes before serving.
Serve
Pull apart and enjoy! Each piece is like a mini caramel apple pie.