How to Make It
In a large bowl, mix the flour with the water and yeast. Cover the bowl and let stand at room temperature overnight.
Grease a large bowl with olive oil. In the bowl of a standing mixer fitted with the dough hook, combine the starter with the flour, water and yeast and mix at medium speed for 8 minutes. Let rest for 20 minutes, then add the salt and mix at medium speed until smooth and tacky, about 8 minutes. Scrape the dough into the greased bowl and shape it into a ball. Cover and let stand in a warm place until doubled in bulk, about 1 hour.
Transfer the dough to a lightly floured work surface and cut it in half. Shape the dough into 2 balls and transfer to a parchment-lined baking sheet. Brush the balls with olive oil, cover with plastic wrap and let stand until doubled in bulk, about 1 hour.
Preheat the oven to 400°. In a large bowl, toss the squash with the 2 tablespoons of olive oil and season with salt and pepper. Spread the slices in a single layer on 2 large rimmed baking sheets and roast for about 15 minutes, until tender; let cool completely. Increase the oven temperature to 450°.
Gently curl the cooled squash slices and press them into the dough. Brush the focaccia with olive oil and bake for 25 to 30 minutes, until risen and browned on top. Transfer to a rack and let cool for 5 minutes. Drizzle honey on top and sprinkle with thyme leaves and Maldon salt. Serve warm.