Cheesy Hasselback Potato Gratin

While having a much too long overdue catching up lunch with friends this past weekend, the question 'what are your goals for the blog in the year ahead? came up. It was a timely question. Not only because the new year brings opportunities for reflection and goal setting, but the blog officially celebrates its' third birthday this week. Where I want the blog to go, what I want its' look and feel to be, and how I want it to evolve are some of the questions I have been mulling over recently. And sooner rather than later I need to come up with some answers!

There have been a variety of changes to the blog over the past three years, some subtle, others markedly discernible. From my perspective, one of the most significant transformations has been the evolution of the photography. Looking back at some of 'first' and 'second' year photos, I realize the bar for what I think is a 'good' photo has changed considerably. And a year from now, when taking another retrospective look back at the photos, I hope the vision I have in my head for the 'look and feel' of the blog is realized. Or is at least getting close. However, I have a feeling that as I change, my vision will change as well.

As you read this blog post your jaw might be dropping and you might be thinking 'well she certainly has her work cut out for her!' And I might reluctantly agree with you considering how I am feeling about these Christmas Day photos of the Cheesy Hasselback Potato Gratin. Which by the way was nothing short of a Herculean feat and a far greater challenge not fully anticipated until I was well into it. (oh well, live and learn). Being one to multi-task with the best of them, getting the holiday meal ready and trying to take photos along the way felt more like I was participating in some sort of holiday Olympics (consider this my sincere attempt at giving an explanation rather than trying to make any excuses). So while these may not be the shiny, perfect photos I envision will someday appear on the blog, I can honestly say this recipe for the Cheesy Hasselback Potato Gratin is pure potato gratin perfection.

Little did I know when I received the newly released The Food Lab: Better Home Cooking Through Science for my birthday earlier this year, that it would be one making multiple best, must-own cookbooks of the year lists. Written by J. Kenji Lopez-Alt, the Serious Eats guru (aka the brilliant nerd king of Internet cooking), the 958 page book will give both your mind and arms a serious workout. Literally and figuratively this book is a weapon. Dominated by more savory than sweet dishes, Lopez-Alt gives us the science underpinning the art of creating both classic and comfort foods. Work your way through this cookbook and your culinary prowess is destined to ascend to level so high your family and friends will brazenly ask, rather than wait or hope, for a meal invitation.

My starting point in what I am now calling an indispensable cookbook was the Cheesy Hasselback Potato Gratin. Paired with a beef tenderloin served with a port wine mushroom sauce, Roasted Balsamic Glazed Onions, and Roasted Brussels Sprouts Gratin, this potato gratin could not have been a more perfect side to help create a memorable Christmas dinner. If by chance you haven't yet fully committed to your New Year's Day menu, let me boldly suggest you make this Cheesy Hasselback Potato Gratin to go along with the ham, lamb, beef, or roasted chicken dish you traditionally make. In case you need to be swayed, I should probably tell you now this creamy layered potato casserole with it's crispy, cheesy browned top has officially achieved the distinction of being placed on my 'last meal' short list.

Potatoes, cheese, cream, garlic, and thyme. Five ingredients are all you need to create what J. Kenji Lopez-Alt calls the ultimate potato casserole. And he delivered on his claim. Russet potatoes peeled and cut into 1/8" slices, finely grated Gruyere (or Comte) and Parmigiano-Reggiano cheese, heavy whipping cream, minced garlic, and coarsely grated thyme come together in a such a way, you cannot help but have an even deeper, greater appreciation for the potato. The vegetable that 'permitted a handful of European nations to assert dominion over most of the world between 1750 and 1950' has a new kind of power in the 21st century.

This Cheesy Hasselback Potato Gratin has the creaminess of a gratin and crunchiness of roasted potatoes. In my world, this means you don't have to make a choice, you can have it all! Having the potatoes go into the pan vertically versus layered horizontally combined with submerging the sliced potatoes in the cream-cheese-herb mixture (ensuring each slice gets coated with the mixture) is why this gratin is able to achieve the two textures. (Notes: (1) If you have a mandoline slicer, the cutting of the potatoes goes quickly and helps to keep the slices uniform. But if you have a sharp knife and good eye, you can achieve the same results. (2) When making the cream-cheese-herb mixture, use only 2/3 of the grated cheeses, saving the remaining 1/3 for sprinkling over the gratin in the final stages of baking).

After coating all of the potato slices, the remaining cream-cheese-herb mixture is poured evenly over the potatoes. I used an aged Gruyere cheese instead of the Comte for no other reason than one of my grocery stores was selling some great aged Gruyere cheese for the holidays at a great price.

The total baking time for the Cheesy Hasselback Potato Gratin is 90 minutes, broken up into three 30 minute segments. In a 400 degree preheated oven, the buttered casserole dish tightly filled with the potatoes are covered with foil and baked for 30 minutes. The foil is then removed and the potatoes return to the oven to bake for another 30 minutes. The reserved grated cheese is then sprinkled over the casserole and it bakes for the final 30 minutes. The finished gratin will have a deep golden brown, crispy top and the potatoes will be knife tender. Visually impressive and insanely delicious, this gratin is fancy dinner party or casual dinner worthy.

Had I assembled the gratin (but adding the remaining cream-cheese-herb mixture right before baking) the night before, I would have been less crazed Christmas morning. If there is one contribution I can make to this recipe, it is you can partially assemble the gratin early the day (covering and refrigerating). I might go so far as to say you might be able to do this night before as well. However, since the overnight assembly theory hasn't been tested (the several hours in the refrigerator idea was), don't try to prove it right or wrong the first time you make the Cheesy Hasselback Potato Gratin.

Sometimes you don't fully appreciate a gift until you put it to use (or until you make it yourself) as the sentiment expressed in any form of thank you changes considerably (and I suppose it could go in either direction). Having now started working my way through some of the recipes in The Food Lab, I am even more grateful for having received it as a gift. This blog posting is more than just sharing a genius recipe with you. It's also a new kind of thank you note.

Recipe
Cheesy Hasselback Potato Gratin (recipe source: The Food Lab: Better Home Cooking Through Science cookbook written by J. Kenji Lopez-Alt)

Ingredients
4 - 4 1/2 pounds russet potatoes, peeled and sliced to 1/8 inch thick
3 ounces finely grated Gruyere or Comte cheese
2 ounces finely ground Parmigiano-Reggiano cheese
2 cups heavy cream
2 - 3 medium cloves of garlic, minced
1 Tablespoon fresh thyme leaves, roughly chopped
2 Tablespoons unsalted butter
Kosher salt and black pepper

Directions
1. Preheat the oven to 400 degrees (F) and have one of the racks centered in the oven.  Spread 2 Tablespoons of unsalted butter evenly in a 2 quart (or 8"x10" or 9"x12") baking dish and set aside.
2. Combine the grated cheeses in a medium sized bowl and mix until blended. Remove 1/3 of the cheese mixture and set aside. 
3. Add heavy cream, minced garlic, thyme leaves to the bowl containing 2/3 of the cheese mixture. Blend together and season generously with kosher salt and pepper.
4. One at a time, add the sliced potatoes, opening slices to allow each one to be fully coated with the cream-cheese-herb mixture. Transfer fully coated potato to prepared pan, setting potato on its' side (aligned vertically).
5. Continue placing potatoes in the baking dish until the entire dish is tightly packed. 
6. Pour the remaining cream-cheese-herb mixture over the potatoes. Note: If assembling the gratin early in the day, wait to pour remaining mixture until ready to bake in the oven.
7. Cover tightly with aluminum foil, place on center rack in the oven and bake for 30 minutes.
8. Remove foil from baking dish and continue baking for another 30 minutes (uncovered).
9. Briefly remove gratin from oven, sprinkle remaining 1/3 cheese mixture over the gratin and return to oven for another 30 minutes of baking.
10. Finished gratin will be golden brown on top and potatoes will be knife tender. Remove gratin from oven. Allow to rest several minutes before serving. Note: If not serving immediately, cover loosely with foil topped with dry dish towel to keep warm.