A Puff Pastry Appetizer with Caramelized onions are just what you need to impress your friends. An easy make ahead appetizer just in time for the Super Bowl. Be warned, they are addictive!
I love to have some go-to appetizers that you can serve for friends, whether you’re having people over for cocktails or to watch the big game. You can always grab some cheese and crackers but having a savory puff pastry warm right out of the oven, is a show stopper.
My favorite appetizers are those that I can make ahead of time and pop in the oven when friends are arriving. Our family’s go-to appetizer has to be Mushroom Logs which we have made a zillion times. They’re extremely simple and impossible to mess up. As good as they are, they can’t compare to a puff pastry appetizer with caramelized onions.
These do take a little more planning than Mushroom Logs, but you can do it days in advance and I promise it’s worth it. What makes French Onion soup so scrumptious is the caramelized onions and that’s what you have in these bite size appetizers, but without the mess of eating a gooey bowl of soup.
You’ll start out by caramelizing the onions, which is not difficult, it just takes some patience and about 30-40 minutes. You can do this step days in advance!
Why you’ll love caramelized onion pastry bites
- All the flavor of a bowl of French onion soup in each bite but without any mess!
- Puff pastry is easy to work with and so delicious.
- You can prepare these ahead of time so you can serve them when you’re ready.
- They are melt-in-your-mouth delicious.
What you’ll need for puff pastry appetizers
- Sweet onions – perfect for caramelizing like a Vidalia, but any onion can be caramelized.
- Fresh thyme – you can use dried too if you don’t have access to fresh.
- Dijon mustard – delicious flavor!
- Chicken stock – if you want to make these vegetarian, use vegetable stock.
- Frozen puff pastry – this buttery pastry is easily frozen, it’s just not worth it to make your own, my favorites are Dufour or Trader Joes brand.
- Gruyere cheese – with a subtle flavor it’s perfect for appetizers, you could use swiss instead.
- Pantry staples – butter, olive oil, egg, sugar, salt, pepper,
How do you make caramelized onion pastry bites
The key to caramelizing onions is patience and low heat. If you turn up the heat too high, the onions will burn instead of caramelizing. By cooking them slow the natural sugars in the onion caramelize creating an intense flavor.
Caramelize the onions
Heat butter and olive oil in a skillet over medium heat. When the butter has melted, add onions and coat with butter mixture. Cook, undisturbed until onions begin to soften, about 4 minutes. Add thyme, mustard, sugar and salt and pepper, stir to combine. Continue to cook stirring every five minutes until golden brown. This will take about 30-40 minutes depending on how thin the onions are and the amount of moisture in the onion. Go by color, not time.
Add chicken stock, cook stirring until liquid is incorporated, about a minute. Remove from heat and let cool slightly. If making in advance refrigerate the onions until you are ready to prepare the pastries.
Roll out two pastry sheets into an equal size square.
Spoon 1 teaspoon of onion mixture in 36 squares about 1 inch apart. You will have 6 rows across and 6 down. Top with some cheese.
Top with second sheet of puff pastry and using your fingers, press the top layer around the filling. Using a pizza cutter, cut into 36 squares and pinch the sides to seal. Use a fork to press the edges together. Place about 2 inches apart on prepared baking sheet. They don’t have to be exact, but no judgement if you use a ruler.
Pro tip: From here you can freeze them for whenever you have friends over or just need to treat yourself with an amazing snack.
Brush with slightly beaten egg and sprinkle with salt and pepper and bake for about 12 minutes until golden brown.
These are delicious warm but trust me they are also great at room temperature. Everyone loves puff pastry and you can easily make this vegetarian by using a vegetable broth instead of chicken stock. You can serve them with a bit of mustard or eat just as they are.
This recipe makes a pretty big batch that can be made weeks ahead and frozen until you’re ready to bake them. If you’re caramelizing onions, go ahead and make some extra, they’re great to add to French onion rounds, a quiche, on top of a burger or just thrown in with your scrambled eggs. They make everything yummy.
FAQs and tips
Prepare the pastry bites right up until you would add the egg wash. Place them in a container to freeze and they’ll be good for about 3 months. Allow them to defrost before following baking instructions.
The best puff pastry is one made with butter. There are two brands in my area that I use, either Dufour or Trader Joes. Trader Joes puff pastry is only available around the holidays.
Pepperidge Farm Puff Pastry does not contain butter so it is a great vegan alternative.
Onions are naturally sweet so when they cook slowly the sugar caramelizes given them a wonderful flavor.
You can shorten the time slightly by covering them at the beginning. This will help the onions to soften a little quicker.
Either a cast iron skillet or a steel pan work best for caramelizing onions. A non-stick skillet will work but you won’t get quite as much flavor, so if you have choice, go with a cast iron skillet.
More great appetizers to share
Puff Pastry Appetizers with Caramelized Onions
- 3 tablespoons butter
- 1 tablespoon olive oil
- 2 large sweet onions thinly slice into ½ moon shapes
- 1 tablespoon fresh thyme
- 1 teaspoon dijon mustard
- 1 teaspoon pepper
- ½ teaspoon salt
- 1 pinch sugar
- 3 tablespoons chicken stock
- 2 sheets frozen puff pastry
- ½ cup gruyere cheese
- 1 egg
- Heat butter and olive oil in a skillet over medium heat. When butter has melted, add onions and coat with butter mixture. Cook, undisturbed until onions begin to soften, about 4 minutes. Add thyme, mustard, sugar and salt and pepper, stir to combine. Cook on low to medium heat stirring about every 5 minutes until they are golden brown, about 30-40 minutes. Reduce heat if they begin to brown too quickly.
- Add chicken stock, cook stirring until liquid is incorporated, about a minute. Remove from heat and let cool slightly.
- Preheat oven to 375º. Place parchment paper on baking sheet.
- Roll out both pastry sheets into an equal sized square.
- Spoon 1 teaspoon of onion mixture in 36 squares about 1 inch apart. You will have 6 rows across and 6 down. Top with some cheese. Top with second sheet of puff pastry and using your fingers, press the top layer around the filling. Using a pizza cutter, cut into 36 squares and pinch the sides to seal. Use a fork to press the edges together. Place about 2 inches apart on prepared baking sheet.
- Brush with slightly beaten egg and sprinkle with salt and pepper.
- Bake for 12-15 minutes until slightly golden, let cool before serving.
Barbara’s Tips + Notes
- Try to use a cast iron skillet or steel pan vs a non stick pan when caramelizing onions.
- Be patient and let the onions cook slowly.
- If your dough gets sticky, place it in the fridge and let it cool down for 10 minutes.
- For the best puff pastry, find one made with butter like Dufour or Trader Joes.