Mix bread flour and instant dry yeast in a stand mixer fitted with a dough hook attachment on medium low speed. Slowly add water in three batches, allowing the flour to absorb water before adding the next batch.

Add sugar and mix thoroughly.

Slowly pour extra virgin olive oil in the center of the dough in four batches, mixing and allowing the flour to absorb the oil before adding the next batch. Use a silicone spatula to flip the dough to help the dough hook catch and knead in the oil. Once all oil is incorporated, add fine sea salt and mix thoroughly until absorbed.

Increase mixer speed to high and mix until you hear a popping sound and the dough wraps around the dough hook, about 1 - 2 minutes.

Roll the dough into a tight ball, place in an oiled bowl three times the size of the dough, cover with plastic wrap, and allow to rise in a warm, draft-free place until tripled in size.

Generously oil the bottom and sides of a baking sheet with extra virgin olive oil. Stretch the dough until it reaches the edge of the sheet pan. If it pulls back, let it rest for 10 minutes, then continue stretching.

Whisk room temperature water and extra virgin olive oil in a small bowl until combined.

Use fingertips to make indentations on top of the focaccia dough. Pour the water and oil mixture evenly on top. Top with gruy?re cheese, thyme, and sea salt flakes.

Cover sheet pan with plastic wrap and allow to proof in a warm place until tripled in size, about 60 minutes.

Preheat oven to 430?F (220?C) with the oven rack in the upper middle slot.

Remove plastic wrap carefully from sheet pan. Bake for 25 - 30 minutes until golden brown and crispy on top. Place focaccia on a cooling rack and cover with a tea towel to cool to room temperature.

To serve, preheat oven to 350?F (180?C), line a baking sheet with parchment paper, and place focaccia slices on top. Bake for 18 - 20 minutes until warmed through and crunchy.