1. In a large mixing bowl, combine the all-purpose flour, salt, and instant yeast. Stir to mix the dry ingredients thoroughly.
2. Add the warm water and olive oil to the dry ingredients. Using a wooden spoon, mix until a sticky dough forms. Remember, the dough will be shaggy and that’s perfectly fine.
3. Cover the bowl with plastic wrap or a damp kitchen towel and let it rise at room temperature for at least 8 hours or overnight. The dough should double in size and be bubbly.
4. Preheat your oven to 425°F (220°C). Generously oil a baking pan and transfer the risen dough onto it. With oiled hands, gently stretch the dough to fit the pan.
5. Using your fingertips, create dimples all over the surface of the dough. Drizzle the pesto over the top, ensuring it seeps into the dimples for maximum flavor penetration.
6. Sprinkle coarse sea salt and fresh rosemary sprigs over the top. Let the dough rest for another 20 minutes.
7. Bake in the preheated oven for 20 to 25 minutes until the focaccia is golden brown and the edges are crispy. The aroma will transport you right back to those cozy kitchen days.
8. Remove from the oven and let it cool slightly before slicing. Serve warm and enjoy every bite!

From my experience, the resting time is crucial in developing that airy, soft texture we all love in focaccia. Patience is key, and the result is well worth the wait.