Crunchy on top, cheesy on the inside – Pearl Onion and Cheese Gratin is a side dish bursting with flavor that your family will love!
I am constantly on the look-out for great side dish recipes – a dish that compliments our main course, one that is simple to make, and one that leaves my family asking me to make it again and again. This onion au gratin recipe definitely fits the bill. The pearl onions and cheddar cheese mix together like a match made in Heaven.
I make this side dish for holidays, celebrations, and even simple family dinners at home. It is a hit every single time. Love the cheesy deliciousness of an au gratin recipe? Try this Cheesy Zucchini Gratin!
PEARL ONION & CHEESE GRATIN
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Onions were something I absolutely did NOT eat as a kid. I swear I had a sixth sense when it came to onions – whenever my mom tried to “sneak” them into a dish, I knew it and refused to even let it touch my plate (now that I have kids, I feel awful for doing that to her…so here’s my apology, mom).
Turns out, I had no idea what amazing tastes I was missing out on. I mean seriously – caramelized onions on top of a burger, crispy fried onions on top of green bean casserole, deep-fried onion rings. I could sing the praises of onions all day long. I wish I could go back in time and tell young me “JUST TRY IT!!!”.
Most recipes you’ll come across in your cooking travels call for white onions, yellow onions, or red onions. But, I’ve found that the most underrated type of onion is the pearl onion. They’re small (oh so cute), mild in flavor (a great way to introduce onions to reluctant eaters!), and they offer a delicious sweet taste to really enrich whatever dish they’re in.
Pearl onions are the perfect main ingredient for a cheese gratin recipe. They soften as they cook, but don’t get too mushy. They pair perfectly with the sharp taste of cheddar cheese. Believe me when I say – you’ll be making this pearl onion & cheese gratin for every special occasion!
- Frozen or fresh pearl onions
- All-purpose flour
- Half and half
- Ground mustard
- Ground nutmeg
- White cheddar cheese
- Fresh breadcrumbs
- Fresh thyme
How to Make Peal Onion & Cheese Gratin
- As any good chef does, start by prepping your dish. Lightly grease your 1-quart shallow baking dish. (I always seem to skip this step when cooking and then end up scrambling to find the dish I need. It’s usually stuffed in the back of the cabinet. *sigh*) Then pre-heat your oven to 350 degrees F.
- Place the onions in a medium saucepan and add enough water to cover them completely. Bring the water to a boil, then lower the heat and simmer for 6 to 8 minutes (or until the onions are just tender!) Drain the onions and set them aside.
- Next, you’re going to make the yummy sauce to coat the onions in: melt the butter over low heat and then add the flour. You’ll want to continually stir it for about a minute so that it doesn’t get clumpy!
- Gradually add in the half-and-half and cook over medium heat. Keep stirring it as you cook – it’ll start to thicken up, that’s when you’re ready for the next step.
- Now mix in your seasonings: salt, pepper, ground mustard, and ground nutmeg.
- Now for the cheesy part! Add in one cup of your shredded cheese and stir until it is melted.
- Gently stir your drained pearl onions into the cheese mixture and then transfer the onions into your prepared baking dish. Sprinkle the rest of the shredded cheese on top – there’s no such thing as too much cheese!
- Now for the crunchy topping! In a small bowl toss the bread crumbs, thyme, and melted butter together. Sprinkle it over the top of the onion mixture. Make sure you cover the whole thing – every bite deserves a crunch!
- Bake for 25 to 30 minutes or until the onions are heated through and the topping is golden brown. Remove the casserole from your oven and enjoy the deliciousness you’ve created!
Pro Tip: If you’re using frozen onions (like I always do) you can thaw and heat them in the microwave or simmer them on the stove for 3 to 4 minutes. Again, only until they’re just tender. They’ll get some more cooking time in the oven!
What does au gratin mean?
I’m pretty sure that “au gratin” is French for “crunchy, cheesy amazingness.” No… not really a direct translation, but that is essentially what it is!! Whenever you see a recipe that is called “au gratin” it means that the dish is covered in breadcrumbs and grated cheese and then browned in the oven.
So you’re taking your favorite sides (like potatoes, onions, or zucchini), adding breadcrumbs and cheese and crisping them up in the oven. What could be better?! You can make so many things au gratin, not just this yummy frozen pearl onion recipe. Try out Au Gratin Potato Casserole or Cheesy Zucchini Gratin!
Looking for some more Side Dish inspiration? Check out these other Real Housemoms favorites!
- Cheesy Roasted Cauliflower
- Red Potato Salad
- Simple Broccoli Casserole
- Sweet Potato Stacks
- Crispy Onion Rings
- more SIDE DISH recipes
Tools used to make this Pearl Onion & Cheese Gratin recipe
Medium Saucepan: I don’t know what I’d do without this saucepan. It gets used in my kitchen every day. The glass lid even has strainer sides so I even have a colander for pasta!
1-Quart Baking Dish: I have so many baking dishes in my house, but this one is definitely my most utilized. I use it for brownies, casseroles, small sheet cakes, basically anything you can think of!
Serving Spoon: I love these spoons! They’re classic, simple, and they get a nice big scoop every time!
*This post originally posted on 11/19/2013.
- 20 ounces fresh pearl onions peeled (see note)
- 2 tablespoons butter
- 2 tablespoons all-purpose flour
- 1 1/4 cups half-and-half
- 1/2 teaspoon salt
- 1/2 teaspoon black pepper
- 1/4 teaspoon dry ground mustard
- 1/8 teaspoon ground nutmeg
- 1 1/2 cups white cheddar cheese shredded, divided
- 3 slices bread
- 2 tablespoons butter melted
- 1 teaspoon chopped fresh thyme
- Preaht oven to 350 degrees F. Coat the bottom and sides of a 1-quart casserole dish with non-stick cooking spray.
- Place pearl onions in a large saucepan and add enough water to cover them. Bring to boil. Then reduce heat and simmer 6 to 8 minutes or until onions are just tender. Drain well and set aside. (see note)
- Melt 2 tablespoons butter in a heavy saucepan over low heat. Add flour, and whisk until smooth. Cook for 1 minute, stirring constantly. Gradually add half-and-half while whisking constantly to prevent lumps. Cook over medium heat, stirring frequently until thickened.
- Add salt, pepper, mustard, and nutmeg. Add 1 cup shredded cheese; stir until cheese melts. Remove from heat, and gently stir in drained onions.
- Pour onion mixture into prepared baking dish. Sprinkle top with remaining 1/2 cup shredded cheese.
- Pulse bread slices in a food processor to make 1 1/4 cups breadcrumbs. Toss breadcrumbs with melted butter and thyme until crumbs are well coated. Sprinkle evenly over cheese.
- Bake uncovered for 25 to 30 minutes or until thoroughly heated and top is golden. Remove from oven and serve warm.