Awesome Sweet Potato Gratin

AWESOME SWEET POTATO GRATIN 1 T. butter, softened 1 1/3 c. heavy whipping cream 2 T. minced garlic 1 T. fresh thyme 3 ½ t. kosher salt, divided 1 ¼ t. black pepper, divided ¼ t. ground nutmeg 2 ¾…