Make the dough: Combine the water with yeast, oil and salt to a mixer bowl. Add 2 cups of all-purpose flour and mix to combine, using the paddle attachment. Cover the bowl with plastic wrap and rest the batter for 20 minutes.
Switch to the dough hook attachment and add the remaining all-purpose flour. Knead on medium-low speed for 15 minutes (speed 3-4 on stand mixer). The dough will be quite sticky but should also be very stretchy and will cling to the hook and clear the sides of the bowl.
Scrape the dough into a lightly oiled bowl, turning once to coat the dough. Cover and set aside in a warm place to double in volume, about 1-1½hours.
Punch down down and turn out onto a lightly floured surface. Knead the dough for a few minutes, then return to the bowl, cover and refrigerate overnight.
In the morning, take the dough out of the refrigerator.
Lightly grease a 1/2 sheet pan with olive oil. Carefully place the dough onto the oiled pan and flip it over to coat the dough with a film of oil.
Use your fingers to spread the dough to about a 1/2-inch thick. You can shape it into desired shape - round, oval or rectangle; cover. Allow the dough to rise for about 1 hour until a finger poked in the dough leaves a dimple.
Preheat the oven to 375°F convection or 400°F regular oven.
Make the streusel: Put the pecans, both sugars and the spices into a food processor. Pulse until the nuts are ground into small chunks. Add the butter and cake flour, process until the streusel forms large clumps.
Prepare pears: Core and cut pears into 1/2-inch cubes.
Assemble focaccia: Lightly brush the top of the risen dough with egg wash to help the toppings stick. Use your fingers to dimple the top of the dough all over.
Press the chunks of pear into the dough, spacing them evenly over the focaccia.
Sprinkle the streusel evenly over the dough, breaking it into small clumps as you go.
Bake for about 30 minutes until puffed and golden brown.
Enjoy warm or at room temperature.