Preheat your oven to 375°F (190°C).
Prep the baking dish with olive oil.
Slice the Yukon Gold potatoes thinly, about 1/8 inch thick.
In a mixing bowl, combine the Boursin cheese, heavy cream, minced garlic, thyme, salt, and pepper.
Layer half of the sliced potatoes in the prepared baking dish, pouring half the cheese mixture over them.
Sprinkle half of the shredded Gruyère cheese over the first layer.
Repeat the process with the remaining potatoes, cheese mixture, and Gruyère cheese on top.
Cover the baking dish with aluminum foil and bake for 45 minutes.
Remove the foil and bake for an additional 15–20 minutes, until the top is golden and bubbly.
Let the scalloped potatoes rest for 10 minutes before serving.