How to make an onion Boil

Ingredients

• 6 medium to small sweet onions

• Salted Kerrygold butter (or any butter, unsalted is fine too)

• Smackalicious Seasoning Mix (or substitute seasoning)

• Heavy-duty aluminum foil

• One oven-safe glass baking dish

( If you enjoyed this post and want to try the ingredients and tools that helped shape the Bloveslife brand, feel free to check them out below! Every view or purchase you make is a way of supporting Blove’s passion and dedication to the community.

Substitute Seasoning (if you don’t have Smackalicious):

• Garlic powder

• Onion powder

• Any dry seasoning mix you like

• OR pre-made Cajun butter sauce (from seafood boils)

Tools

• Sharp knife

• Glass baking dish

• Heavy-duty foil

Instructions

Step 1: Prepare the Onions

• Take 6 sweet onions.

• Locate the “bulb” or sprout area on top.

• Use a knife to carve out that part, creating a deep pocket.

• Make sure the pocket is deep enough to hold plenty of butter.

• Save the removed onion pieces for another recipe if you’d like.

Step 2: Fill with Butter

• Take your salted Kerrygold butter.

• Stuff each onion pocket full of butter.

• Use a knife to smooth and press it in tightly — don’t be shy with the butter!

• The more butter, the better the flavor.

Step 3: Wrap the Onions

• Cut sheets of heavy-duty foil — important: use the thick kind so it won’t tear.

• Place one onion in the center of each foil sheet.

• Sprinkle with Smackalicious seasoning mix on top.

  Alternatively:

  • Drizzle with Cajun butter sauce, or

  • Sprinkle with garlic powder, onion powder, and your favorite dry seasonings.

• Wrap each onion tightly so there are no holes or openings.

• Repeat with all six onions.

Step 4: Bake

• Place all wrapped onions into your glass baking dish.

• Preheat oven to 375°F (190°C).

• Bake for 1 hour to 1 hour and 20 minutes:

  • 1 hour for medium/small onions

  • Add 10–15 minutes for larger ones

• Bake until the onions are completely soft and tender.

Step 5: Serve & Enjoy

• Carefully remove from oven — they’ll be very hot!

• Unwrap the foil gently.

• The onions should be buttery, soft, and easy to pull apart layer by layer.

• Serve as a side dish or pair with:

  • Grilled steak

  • Roasted chicken

  • Pork

  • Shrimp

  • Seafood boil dishes

Notes

• IMPORTANT: Always use heavy-duty foil — thin foil tears easily.

• Wrap tightly so the onions cook evenly.

• Sweet onions are thick and need time to get soft all the way through.

• The pocket must be deep enough to hold plenty of butter.

• You can prep several onions ahead of time and refrigerate them for later use.

Money-Saving Tips

• Buy sweet onions in bulk:

  • Costco: 5 lb bag ~ $4.40

  • Sam’s Club: 10 lb bag ~ $8

• Buying in bulk saves much more than buying individual onions.

Results

Your onions will be:

• Melt-in-your-mouth tender

• Naturally sweet

• Soaked in buttery, savory flavor

• Fragrant and irresistible

• Easy to peel layer by layer

Prep time: 15–20 minutes
Cook time: 1 hour – 1 hour 20 minutes
Servings: 6