Preheat oven to 400 degrees. Spray a 9 x 13-inch baking dish with cooking spray.
In a medium, heavy saucepan, add whipping cream and Boursin cheese. Stir over medium heat until cheese is melted. Set aside.
Arrange half of sliced potatoes in baking dish in overlapping rows. Season with 1 tsp. of kosher salt and 1/2 tsp. pepper. Pour half of cheese mixture over. Arrange remaining potatoes over potatoes in dish. Season with remaining 1 tsp. salt and 1/2 tsp. pepper. Top with remaining cheese mixture.
Bake uncovered for 1 hour, or until potatoes are tender when pierced with knife.
This recipe was adapted from the Bon Appetite Entertaining with Style cookbook, copyright 1996 Conde Nast Publications, recipe titled as Potato Gratin with Boursin.