Slice the two onions thinly and cook them over medium heat in a pan with 1 tablespoon of olive oil until soft and golden brown, about 30 minutes, stirring occasionally. Set aside to cool. 2 large yellow onions
In a large bowl, combine instant or active dry yeast and lukewarm water. If using active dry yeast, let it dissolve in the lukewarm water for 5 minutes first. 360 g water, 2 tsp instant yeast
Add flour, pumpkin puree and salt. Mix with a wooden spoon or spatula to create a shaggy, very wet dough. Let the dough rest for 15 minutes. 560 g all-purpose flour, 160 g pumpkin puree, 1 ½ teaspoon fine salt
After resting, perform 3-4 sets of stretches and folds over the next hour, one set every 15 minutes. To do a stretch and fold, wet your hands well with water, then grab one side of the dough, stretch it up, and fold it over itself. Turn the bowl and repeat on all sides. The dough will become smoother and stronger with each set.
Drizzle 2-3 tablespoons of olive oil into a 9x13-inch baking pan. Transfer the dough into the oiled pan. Let it rest for 5-10 minutes, then use oiled fingers to gently stretch the dough to fill the pan. If the dough resists, give it a few minutes to relax and try again.
Let the dough rise in a warm place for about 1 hour, or until it doubles in size and jiggles when you shake the pan. While the dough rises, preheat your oven to 450°F (230°C).
Once the dough has risen, drizzle a bit more olive oil over the surface. Use oiled fingers to create deep dimples all over the top of the dough.
Spread the caramelised onions over the dough, pressing them into the dough lightly. Strip the rosemary needles from the stems and press these into the dough. Sprinkle the top with flaky salt.Bake the focaccia for 25-30 minutes until it’s puffed up, deep golden brown, and the edges pull away from the pan. Let the focaccia cool in the pan for 3-4 minutes, then carefully remove it and transfer to a wire rack to cool further before serving. 2-3 sprigs fresh rosemary, Flaky salt for topping