In a large bowl, mix together the flour, yeast, 3 tablespoons of olive oil, and sea salt.

Gradually add the water while mixing slowly until the dough is well combined and sticky.

Allow the dough to rest for a few minutes to develop structure.

Cover the bowl with a clean kitchen towel or plastic wrap and let it rest in a warm place for 30 to 40 minutes, until it doubles in size.

Add the remaining olive oil and lightly oil your hands to prevent sticking.

Gently fold the dough by lifting it from the edges and folding it over itself several times to strengthen its structure.

Cover the bowl with plastic wrap and refrigerate the dough for at least 8 hours or overnight (up to 12 hours).

Grease a muffin tin with about ½ tablespoon of olive oil in each cup.

Cut the dough into equal portions and shape them into smooth balls.

Place each dough ball into the muffin tin.

Let the dough rest in the tin at room temperature for 40 to 60 minutes, or until it doubles in size and has bubbles on top.

Preheat the oven to 400°F.

Drizzle the remaining ½ tablespoon of olive oil over the dough and use oiled fingers to create dimples by gently pressing into the dough.

Sprinkle fresh rosemary, green olives, and flaky sea salt evenly over the top.

Bake the muffin tray in the preheated oven for 25 to 30 minutes, or until the focaccia is golden brown on top.

Remove the focaccia from the oven and take each muffin out of the pan.

Serve warm or at room temperature.