Preheat oven to 400F.
In a saucepan over medium heat, add: unsalted butter, thyme, sage, garlic, half & half, kosher salt, and black pepper. Heat until butter is melted and cream is warm, about 5-7 minutes.
While the herb cream warms, slice the potatoes. Using a mandoline, thinly slice potatoes using a knife glove or a guard. Place in a large bowl.
Pour herb cream over sliced potatoes and add half of the gruyere and pecorino Romano cheese. Toss the sliced potatoes until they are fully coated.
In a non-stick muffin pan (if you don't have non-stick, lightly grease), start stacking the potato slices all the way to the top of the muffin tin. Take the remaining herb cream and evenly disperse over the stacks. Top with the remaining cheese.
Cover the muffin pan with parchment paper followed by foil (the parchment will keep the cheese from sticking). Place muffin tin in a sheet pan and place in the oven.
Roast for 30 minutes covered, then remove foil/parchment and roast an additional 20 minutes until tops are browned and bubbling.
Once the potatoes are done cooking, use a knife or spoon to loosen around the sides and carefully scoop out of the tins. Enjoy!