greasy au gratin potatoes

I had a recipe for au gratin potatoes, that I made that was wonderful the first couple of times, then after that they creme frache is separating & they are incredibly greasy (still taste good but yucky texture). I have moved the rack in the oven, thought maybe oven was too hot so tried moving to lower rack, & tried decreasing the temp, & tried starting at a lower temp too. All mean the potatoes take forever to cook & still the same problem. Any suggestions?

If I give up the creme frache as good as that tastes & just us plain old sour cream will that be less likely to do this?

1 ½ C CRÈME FRAICHE1/3 C WHIPPING CREAM
3 lb YUKON GOLD POTATOES 1 ½ t SALT
¾ t GROUND BLACK PEPPER3/4 t DRIED THYME

Peel & slice potatoes 1/8” thick. Preheat oven to 400 deg. Rack in center. Generously butter 9x13 glass pan. Whisk creme fraiche & whipping crème in med. Bowl to blend. Arrange 1/3 of potato slices in bottom of baking dish, overlapping slightly. Sprinkle with ½ t salt, ¼ t pepper, & 1/4 t thyme. Drop 1/3 of crème fraiche mixture (about generous ½ C) in dollops over potatoes, then spread evenly over (layer will be very thin). Repeat layering 2 more times. Bake gratin 30 minutes. Reduce oven temp to 350 and continue to bake until potatoes are tender & top is golden brown, about 25 minutes longer. Let gratin rest 20 minutes before serving.

It will be more likely to do that. Try adding some flour to your creme fraiche and whipping cream mixture.

any idea why it's doing it to begin with?

The recipe you give is a far cry from the traditional potato au gratin. First there is no cheese either in or on top. Second by introducing Frache into heavy cream you are bringing in an acid which like sour cream will curdle at boiling point.400 for 1/2 hour will boil at edges and sometime right thru. Next even though you used yuke gold before, this time they may be less starchy, therefore absorbing less of liquid and more chance of curdleing. This almost sounds like a scalloped potato recipe. Try useing a little Bechamel and heavy cream. good luck

Absolutely. The cream is curdling from being cooked too long and too hot. It's entirely a matter of temperature, temperature management and technique. Chef Ed touched on this.

In my opinion, the creme fraiche isn't a problem.

The proper way to cook potatoes in a gratin with cream and/or creme fraiche is to LOOK. I know it sounds silly, but there you go. That's cooking. You have to watch those spuds closely when they're "nearly done." As soon as you see little drops of yellow coming up the sides, you get that gratin out of the oven whether it's brown on top or not. That yellow is the butter fat beginning to separate out of the cream, i.e., curdling -- and that is the exact right moment to remove. You can cook at a lower temperature, or different rack, or try one of a number of different tricks to get a little more cooking time on the potatoes and/or a little more browning on the top -- but those things are incidental.

Yellow spots -- out it comes.

The name au gratin has a meaning in American restaurant service that it does not have in French. That's why you're hearing about cheese. You're making a gratin of potatoes and have permission to call it what you will, as well as to use creme fraiche which is not only a perfectly good ingredient but traditional in dishes of this type as well.

Let it set up outside of the oven for five minutes, run it under the broiler to brown the top, and you can call it a gratinee. That will confound them.

The whole bechamel/flour thing does help hold the cream together, but it's more of a commercial trick, and shouldn't be necessary for a home cook who has the luxury of doing only two or three things at a time. Attention is one of the luxuries home cooks have, and watching the finish is better.

Let me know how this works for you, and for heaven's sake take a gander at my newest blog entry and let me know what you think. Please.

BDL

I've never succeeded with classic potato gratin or gratin dauphinois. It always curdles for me. And when it curdles, the fats are released from suspension, breaking your sauce.

I have a fondness for the mainstream american cheesy potatoes au gratin. And I get the best results with a bechamel base to help hold it together. The classic version uses russets which are starchier than your yukon golds. They'd release some of their starch into the sauce as it bakes helping hold it together a bit more. The Yukons don't do that as well.

The other trick I've picked up is to barely simmer the sliced russets in the milk (or half and half) for bechamel for about 10 minutes. This par cooks the potatoes, releases their starch into the milk and heats the milk up for making the bechamel. DO NOT LET IT BOIL. So with par-cooked potatoes, I don't have to bake it as long which protects the sauce from boiling around the edges and curdling.

Of course, all my suggestions completely differ from your original recipe. So I'll try and apply my ideas to your recipe.

You could simmer your Yukon slices in your cream. But you don't really have enough cream for that, so just simmer them in water then drain them well. Don't cook them fully, just a bit. You won't be geting the starch benefit, but you won't have to cook the assembled dish as long so you should be able to keep the sauce from boiling too much and curdling.

As Ed and cheflayne cpoints out, some starch to bind your sauce is needed especially where you're using a medium starch potato. Bechamel uses cooked flour and is what I do. You might try mixing some flour into your dairy. If you find that it ends up with a floury taste as the flour isn't getting sufficiently cooked, try using some corn starch instead.

And just for a bit more flavor, rub your baking dish with a cut clove of garilc right before you assemble your gratin.

Phil

Hi RZN,

If you want to stick to the core concept of your recipe (i.e. not using a starch liaison to help bind the fat) the only other suggestion I would add to BDL's is that you might want to give your potato slices a good squeeze before layering them. Potatoes can contain a lot of water, if you ring it out it they will cook faster and will absorb more of the creamy goodness.

Oh, one last personal quibble with your recipe. It probably makes little real difference but my inclination would be to season your cream mixture rather than sprinkling salt/pepper between layers. Its an option.

--Al

The best method (for me, anyways) is to slice the spuds in about 1/8" thick slices and just barely cover them with milk. Flavour the milk anyway you want (bay leaf, garlic, nutmeg, etc), poach until potatoes are cooked, but still hard. Remove the spuds and layer/shingle them as desired. Bring the milk to a boil, thicken slightly with a white wash, and "nap" the spuds. Keeps well on mise en place, bakes great without cheese.