Caramelized Onion and Mushroom pastry bites on a white tray served for a party.

Caramelized Onion and Mushroom Puff Pastry Bites

Savory Caramelized Onion and Mushroom Puff Pastry Bites make a great appetizer for your holiday gatherings and parties. Make a big tray!
Course Appetizer
Cuisine American
Keyword Caramelized Onion and Mushroom Puff Pastry Bites
Prep Time 1 hour 30 minutes
Total Time 1 hour 30 minutes
Servings 64
Calories 76kcal
Author Jennifer Quisenberry


Puff Pastry:

  • 1 package frozen puff pastry
  • 2 eggs beaten
  • flour for rolling

Caramelized Onions:

  • 4 large yellow onions
  • ¼ c. unsalted butter
  • 3 dry white wine
  • salt and pepper to taste

Marinated Mushrooms:

  • 8 oz. sliced baby Portobello mushrooms cleaned and patted dry
  • ¼ c. Marsala wine
  • salt and pepper to taste
  • 2 olive oil
  • 8 oz. Applewood smoked cheddar grated
  • 3 fresh thyme leaves only


  • Thaw puff pastry overnight in the refrigerator.
  • In a medium glass bowl, combine mushrooms and Marsala wine. Season with salt and pepper, to taste. Toss to coat. Marinate for 20 minutes at room temperature. Drain excess moisture before cooking.
  • Heat 2 olive oil in a large skillet over medium-high heat. Once oil is hot, add marinated mushrooms and sauté until browned and tender, approximately 5 - 7 minutes. Remove from heat and transfer to a bowl. Set aside.
  • To caramelize onions, slice off both ends and remove the papery outer layers. Cut onion in half lengthwise (from tip to root). Then cut each half across the middle to form four sections. Cut each section lengthwise into strips.
  • Tip: Don’t cut the onions too thin, or they may burn while cooking.
  • Over medium heat, melt butter in a large skillet with high sides. (For best results, do not use a non-stick pan). Add onions and stir with a wooden spoon until coated with butter.
  • Cook onions over medium heat for approximately 45 – 50 minutes, stirring every 5 minutes or so to ensure they cook evenly and don’t stick to the pan. The exact cooking time will vary based on several factors, including the age of the onions and how many you cook at one time.
  • Once the onions reach the desired depth of color, add white wine to deglaze the bottom of the pan. Add more liquid if necessary to scrape up all the brown bits and then salt and pepper the onions, to taste. Remove from heat and let cool in pan until ready to use. Once cool, transfer any unused onions to an airtight container for future use.
  • Preheat oven to 375 degrees. Line two large, rimmed baking sheets with parchment paper and set aside.
  • Cut thawed puff pastry dough in half and roll out on a lightly floured surface. With a sharp knife or pizza cutter, cut the puff pastry sheet into 32 equally sized rectangles. (See picture). Transfer puff pastry pieces to a prepared baking sheet and place in the freezer for 10 minutes.
  • Repeat the above steps for the other half of the puff pastry.
  • Remove baking sheets from freezer and let sit for a couple of minutes before brushing each piece with the beaten egg.
  • Carefully arrange equal amounts of grated cheddar cheese, caramelized onions and sautéed mushrooms on each piece of puff pastry. Sprinkle each with fresh thyme leaves.
  • Place baking sheets in the preheated oven and bake for 10-15 minutes before rotating each baking sheet to ensure the pastry bites cook evenly. Continue cooking until the pastry is golden brown, approximately 8-10 minutes.


TIP: Put the cheese in the freezer for 10 minutes before grating for best results.
Tip: Don’t cut the onions too thin, or they may burn while cooking.
Please note that nutrition facts are subject to change based on your choice of ingredients.