Prepare the Simple & Delicious Focaccia Dough (recipe linked above)
While the dough is rising, 1 tbsp of olive oil in a large pan on medium heat.
Add onions and a pinch of salt, stir and cover, letting onions soften for 5 minutes.
Remove lid, add the butter, and reduce heat to low. Allow onions to continue to caramelize for 30-40 minutes. Stirring occasionally.
Once a deep golden brown, add the finely chopped garlic, thyme, salt and black pepper to the skillet. Cook until garlic is fragrant, about 2 minutes.
Pour wine into the skillet and stir, scraping any browned bits from the bottom of the pan.
Add the beef broth to the skillet and bring the mixture to a simmer. Allow the onions to cook for 10-15 minutes or until the liquid is almost fully reduced.
Remove from heat and let cool until the focaccia is ready to assemble.
Grate the Gruyere Cheese.