Preheat your oven to 400°F (200°C).

Start by trimming the stem end (top) off each onion. Do not cut the root end—this keeps the onion intact as it roasts. Peel away the outer skin layers and discard.

Next, take a sharp knife and cut an “X” about halfway down into the top of each onion, allowing the seasoning and butter to soak deep into the layers.

In a small bowl, combine 4 tablespoons softened butter, 2 teaspoons Cajun seasoning, 1 teaspoon garlic powder, and salt and pepper to taste. Mash and mix well until you have a smooth, seasoned compound butter.

Place each onion on a square of foil. Gently pry apart the X-shaped cuts on top, and press 1 tablespoon of Cajun butter into the crevice of each onion.

Top each with a lemon wedge, then loosely wrap the foil around each onion to form a pouch. Leave some space inside for steam to circulate, which helps the onion soften fully.

Optional: For an even smokier flavor, sprinkle a touch of smoked paprika or add a few dashes of hot sauce before sealing the foil.

Arrange the foil-wrapped onions on a baking sheet. Roast for 45 to 60 minutes, depending on the size of your onions.

You’ll know they’re ready when the onions feel soft to the touch and release a sweet, almost caramel-like aroma. The butter will be bubbling, and the edges may start to brown slightly.

Carefully unwrap the foil packets (watch for steam!) and transfer the onions to bowls or small plates. Spoon the melted Cajun butter from the foil over each onion.

Garnish with chopped parsley for freshness. Add cheese, hot sauce, or extra seasoning if desired. Serve warm.