Cheesy Skillet French Onion Dip with Warm Crusty Crostini Tips, FAQ & printable recipe

Tips for success

For the deepest onion flavor, take the time to truly caramelize the onions until they are dark and jammy—this can take up to 30 minutes.

Don’t be tempted to rush it; high heat will burn the onions before they develop their natural sweetness. If the onions stick to the pan, add a splash of water or broth and scrape up the browned bits. This adds even more flavor to the dip.

To make crostini at home, slice a baguette into 1/4-inch rounds, brush with olive oil, and toast in a 375°F (190°C) oven for 8–10 minutes until golden and crisp.

For a garlic flavor, rub the warm crostini with a cut garlic clove. Make extra—they’ll disappear quickly. If you have leftover dip, it’s also delicious spread on sandwiches or burgers.

Variations

• Bacon French Onion Dip: Add 1/2 cup cooked, crumbled bacon to the dip mixture before baking. The smoky saltiness pairs beautifully with the sweet onions and Gruyère. Garnish with additional bacon bits and chives for extra flavor.
• Herb and Garlic Twist: Stir in 2 cloves of minced garlic with the onions during the last 5 minutes of caramelization. Add 1 tablespoon of chopped fresh chives or parsley to the dip mixture. This adds a fresh, savory note that complements the cheese.
• Spicy French Onion Dip: Add 1/2 teaspoon of red pepper flakes or a dash of hot sauce to the dip mixture for a subtle kick. The heat balances the sweetness of the onions and adds a new dimension. Serve with extra hot sauce on the side.
• Mushroom French Onion Dip: Sauté 8 oz (225 g) sliced mushrooms with the onions until browned and tender. Fold them into the dip mixture along with the onions. The earthy mushrooms add depth and make the dip more substantial.

Storage and make-ahead

Fridge

Store leftover dip in an airtight container in the refrigerator for up to 4 days. Reheat gently until hot and bubbly before serving.

Freezer

The baked dip can be frozen for up to 2 months. Thaw overnight in the refrigerator, then reheat in a 350°F (175°C) oven until hot and bubbling.

Reheat

To reheat, place the dip in an oven-safe skillet or baking dish and warm at 350°F (175°C) for 10–15 minutes, or until hot and bubbly.

Store leftover dip in an airtight container in the refrigerator for up to 4 days. The dip will thicken as it cools; reheat gently in the microwave or oven until hot and bubbly.

Stir before serving to redistribute the creamy texture. The crostini are best stored separately in a sealed bag at room temperature for up to 2 days; re-crisp them in a toaster or oven before serving.

The dip can be fully assembled (without baking) up to 2 days ahead. Cover the skillet with plastic wrap and refrigerate. When ready to serve, bake as directed, adding 5–10 minutes to the baking time to ensure it’s heated through.

The caramelized onions can also be made up to 3 days ahead and refrigerated, allowing you to assemble the dip quickly on the day of serving.

Serving ideas

Serve the dip warm, straight from the skillet, on a heatproof trivet. Provide a basket of warm crusty crostini for dipping, along with spoons for scooping. The dip is rich and indulgent, so a little goes a long way—perfect for sharing. For a party, set out small plates and napkins, and encourage guests to dunk generously.

This dip is also delicious served with fresh vegetables like carrot sticks, celery, or bell pepper strips for a lighter option. To keep the crostini warm, wrap them in a clean kitchen towel and place in a low oven (200°F/95°C) until ready to serve. For a festive touch, garnish with extra fresh thyme or a sprinkle of cracked black pepper.

Frequently asked questions

Recipe card

Cheesy Skillet French Onion Dip with Warm Crusty Crostini

Prep 15 minCook 50 minTotal 1 h 5 minServes 8

Ingredients

• 3 large yellow onions, thinly sliced
• 2 tbsp butter
• 1 tbsp olive oil
• 1 tsp brown sugar
• 1 tsp fresh thyme leaves, plus more for garnish
• 200 g (7 oz) cream cheese, softened
• 1/2 cup sour cream
• 1/4 cup mayonnaise
• 1 cup shredded Gruyère cheese
• 1/4 cup grated Parmesan cheese
• Warm crusty crostini (baguette slices toasted), for serving

Instructions

1. In a large skillet, melt the butter with the olive oil over medium heat. Add the sliced onions, brown sugar, and fresh thyme. Cook slowly, stirring occasionally, for about 30 minutes, until the onions are deeply caramelized, jammy, and dark mahogany in color. Reduce heat if they begin to scorch.
2. In a mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Stir until smooth and well blended. Add the warm caramelized onions, 1 cup of shredded Gruyère, and the grated Parmesan. Mix until everything is evenly incorporated.
3. Preheat the oven to 375°F (190°C). Transfer the dip mixture into an 8-inch cast iron skillet and smooth the top with a spatula. Sprinkle the remaining Gruyère cheese evenly over the surface, covering the dip completely.
4. Place the skillet in the preheated oven and bake for 20 minutes, until the dip is hot and bubbling and the cheese on top is melted and browned in spots. The edges should be golden and the center should be molten and bubbly.
5. Remove the skillet from the oven and let it cool for a few minutes. Garnish with fresh thyme leaves. Serve warm with warm crusty crostini for dipping, encouraging guests to scoop deep into the molten cheese center.

Contains: gluten, milk, eggs

Estimated nutrition per serving

Calories

320

Protein

9 g

Carbohydrates

12 g

Fat

26 g

Automatic estimate from the ingredient list, not laboratory-verified.