Preheat oven to 375 degrees. Butter a 9x9 baking dish.
Rinse and peel the turnips. Slice turnips into 1/4 inch thick slices using a sharp knife, mandoline, or food processor.
Arrange 1/3 of the turnips into the prepared baking dish.
Combine the garlic powder, salt, and pepper and sprinkle the turnips with 1/3 of the seasoning.
Combine the cheeses and sprinkle the turnips with 1/3 of the cheese.
Repeat the layers twice more ending with cheese.
Pour the cream over the top of the mixture.
Cover dish tightly with foil and bake for 50 minutes.
Remove the foil and continue baking for 20 minutes or until the top is lightly browned and the turnips are tender.
Cool 5 minutes before serving.
Video
Notes
Use the smallest turnips you can find as they'll taste less bitter than larger turnips.Any mix of cheese you like works well, but I find mild cheese such as Monterey Jack works well with the flavor of turnips.