Caramelized Onion Tart

Recipe and Image Courtesy of Sandra’s Easy Cooking

Our family, including our beloved Grandma Lorraine, who famously told us that “there’s not much in life that can’t be made better with butter,” has made developing the perfect batch of butter our family legacy. This goal is more than 125 years in the making, a passion passed on from generation to generation, including our children, who make up generation six.

The end result is a line high butterfat butter in multiple, dreamy flavors, from sea salt butter to the garlic herb variety.

You can grab the rolled version of our butter — or the classic sticks you’ll often find on store shelves — from your local market or specialty store, by using our location tool.

Be sure to keep up with our latest creations through our FacebookPinterest, or Instagram pages.

So, without further ado, here’s our recipe for a Caramelized Onion Tart:

Prep Time: 70 Minutes
Servings: 6


  • 2 Sheets Puff Pastry
  • 2 pounds Onions, sliced into thicker rings, preferably Vidalia Onions
  • 3 tablespoons Minerva Dairy Unsalted Butter
  • 1 tablespoon Olive Oil
  • 1/4 – 1/2 teaspoon Salt
  • 1 teaspoon Ground Black Pepper
  • 2 Sprigs of Fresh Thyme, plus for garnish
  • 4 tablespoons Creme Fraiche 



  1. Melt the butter, then add oil in a large skillet.  Add thick onion slices and turn the heat to medium.  Stir to coat for a bit and do not touch it until you see the onion changing color from the bottom.  You can check by flipping once or twice after 5 to 7 minutes.
  2. This is the beginning of caramelization.  I do not add sugar, but I use sweet yellow onions which will give you an excellent caramelization of onions.
  3. Now, add the thyme, salt, and ground black pepper to the skillet and stir.  Turn the heat to medium-low heat until the onions are completely translucent and caramelized.  It will take around 30 to 40 minutes depending on your stove, skillet, etc.  Remove from heat and allow to cool slightly.


  1. Preheat oven to 400 degrees Fahrenheit (190C).
  2. Thaw your frozen puff pastry, preferably in the fridge, overnight.
  3. Unfold your pastry only when fully thawed.
  4. Flour your work surface and your rolling pin.  Use restraint with your rolling pin and just slightly roll.  Use a fork and make small punching holes all around the bottom of the puff pastry.
  5. Add Creme Fraiche on the top of the pastry then slightly fold ends of the pastry, as shown on the pic.  If you do not have Creme Fraiche, check notes below.
  6. As you can see on step by step instructions make sure the pastry has four edges in order to hold the onions.  You may make it as traditionally rectangular or bake in the circular baking tart pan.
  7. Bake between 15 and 17 minutes, depending on your oven.  The pastry needs to be golden.
  8. Take it out and allow it to cool down for a minute or two before slicing.



  1. Mix 1 cup heavy cream and 1/4 cup whole milk sour cream together.
  2. I like mixing it in the jar or a container with a fitted lid, but you can pour the misture into a jar as well, cover and let stand in a warm place for about 8 hours.
  3. Then stir and refrigerate for 24 hours before serving

SANDRA’s easy cooking

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