Alsatian Caramelized Onion Pizza is my take on the Trader Joe’s Tart d’Alsace. I’ll tell you how to make overnight caramelized onions, too.
The first time I had Tart d’Alsace, they were offering small samples of it. I fell in love and bought one right away. Recently, I had an abundance of onions, and I decided to make it at home. What I made was well worth it, and not that difficult. I’m very grateful to those bakers testing their ovens.
The dish was created by Germanic farmers from Alsace, Baden and the Palatinate who used to bake bread once a week. A Flammkuchen would be used to test the heat of their wood-fired ovens. At the peak of its temperature, the oven would also have the ideal conditions in which to bake a Flammkuchen. The embers would be pushed aside to make room for the cake in the middle of the oven, and the intense heat would be able to bake it in 1 or 2 minutes. The crust that forms the border of the Flammkuchen would be nearly burned by the flames. The result resembles a thin pizza.
Overnight Caramelized Onions
I think that caramelized onions scare people. After all, it means slicing a lot of onions thinly, then setting them in a pot at low heat and simmer down to almost nothing – and you have to babysit and watch it. No, thank you!
But, not anymore. I followed advice from a Facebook group member who said she put her onions in the slow cooker overnight. A game changer! No more having to babysit, stir, or anything else.
It’s an effortless procedure. Slice about six onions thinly, then dump them in the well of a slow cooker with a couple of tablespoons of butter and a little salt and pepper. Put the machine on low, cover it, and come back 12 hours later. All the onions will be beautifully brown and soft. There will be liquid. If you want to make French Onion soup, stop there. If you’re going to use them for something else, like this pizza, leave the top slightly ajar and let them keep cooking for another 3 hours.
You can do this in your sleep – literally.
~~ -- For the Caramelized Onions -- ~~
- 6 Onions, thinly sliced
- 2 tablespoon butter
- 1/4 teaspoon Kosher Salt
- 1/4 teaspoon Black pepper, freshly ground
~~ -- For the Tart -- ~~
- 1 pizza dough, rolled out thinly
- 1/4 cup Sour cream
- 1 cup Swiss, shredded or sliced
- 1/4 cup Ham, thinly sliced
- 4 tablespoon parmesan, grated
- 2 Mushrooms, thinly sliced (optional)
- 8 Black olives, whole or sliced (optional)
Make the Caramelized Onions
- Slice the onions thinly, then dump them in the well of a slow cooker with the butter, salt, and pepper. Put the machine on low, cover it, and come back 12 hours later. All the onions will be beautifully brown and soft. There will be a liquid that needs to be evaporated. Leave the top slightly ajar and let them keep cooking for another 3 hours. You only need about 1/2 cup of these onions, just freeze the rest.
Make the Tart
- Preheat your oven to 500 F/ 260 C. It's going to take a while to get that hot, so be aware of that.
- Roll the dough out thinly. You can use a pizza pan if you want, or you can put parchment paper on a pizza peel and put the dough on that.
- Spread the sour cream on the pizza dough and cover it loosely with some of the parmesan.
- Put the onions all around with the swiss cheese, ham, mushrooms, and olives, if using. Cover with more grated parmesan.
- Bake for 15 minutes, checking at 12 minutes, or until the crust has started to brown and the cheese has all melted.