In a large bowl, combine the bread flour, instant dry yeast, granulated sugar, and fine sea salt.

Add warm water and room temperature water, then mix until a dough forms.

Knead the dough on a floured surface for about 10 minutes until smooth and elastic.

Incorporate the olive oil into the dough until well combined.

Place the dough in a greased bowl, cover, and let it rise in a warm place for about 2 hours, or until doubled in size.

Once risen, gently deflate the dough and spread it into a greased baking pan.

Top the dough with the gruyère cheese and fresh thyme leaves.

Allow the dough to rise for another 30 minutes.

Preheat the oven to 400°F (200°C).

Sprinkle Maldon sea salt flakes over the top of the focaccia.

Bake for 50 minutes or until golden brown.

Let cool slightly before serving.