In a bowl, combine water, milk, yeast, honey, and olive oil.
In another bowl, mix the flour and salt. Gradually add the liquid mixture, stirring until a smooth dough forms.
Place the dough in a greased bowl, cover with a cloth or plastic wrap, and let rest in an oven with the light on for 30 minutes.
After this rest, perform 4 consecutive stretch-and-folds.
Transfer the bowl to the refrigerator. Every 30 minutes, repeat the same 4 stretch-and-folds, for a total of 3 more times.
Once all 4 series are completed (1 at room temperature + 3 in the fridge), let the dough rest in the refrigerator for 12 to 24 hours.
In a bowl, toss the apples with brown sugar, cinnamon, and a drizzle of olive oil.
Transfer the dough to a greased rectangular pan. Spread with your fingers. Place half of the apples in the center, fold the dough to enclose the filling, then gently flip so the seams are underneath.
Cover and let rise for 1 ½ hours, or until doubled in size.
Preheat the oven to 375 °F (190 °C). Top with the remaining apples and press dimples into the dough with damp fingers.
Bake for 30–35 minutes. Let cool for 15–20 minutes before serving.
For the caramel sauce, whisk the olive oil and cold maple syrup vigorously until thickened. Add a pinch of salt.
Serve the apple and cinnamon focaccia drizzled with caramel sauce.
