Ruth’s Chris Mushroom & Gruyère Tart – Elegant Appetizer

This mushroom and Gruyère tart is the kind of appetizer that immediately sets a refined tone. Inspired by classic steakhouse flavors, it combines buttery puff pastry with savory mushrooms and nutty Gruyère for a dish that feels elegant yet approachable.

The mushrooms are slowly sautéed until golden and deeply flavorful, building a rich base that pairs beautifully with the sharp, creamy notes of Gruyère cheese. Fresh thyme adds an aromatic, earthy layer that elevates the tart without overpowering it.

A light custard of cream, egg, and Dijon mustard ties everything together, giving the filling a silky texture while enhancing the savory depth. As the tart bakes, the pastry puffs and crisps while the center becomes luscious and bubbling.

Perfect for dinner parties, holidays, or cocktail gatherings, this tart can be sliced into small bites or generous wedges. It looks impressive on the table, but it’s surprisingly simple to prepare, making it a reliable go-to when you want something that feels special.

Serve it warm straight from the oven or at room temperature with a glass of wine for a true steakhouse-style appetizer experience at home.

Servings: 6–8 appetizer portions
Prep Time: 20 minutes
Cook Time: 30 minutes
Total Time: 50 minutes

Ingredients

• 1 sheet puff pastry, thawed
• 2 tablespoons olive oil
• 2 tablespoons butter
• 8 oz mushrooms (cremini or button), thinly sliced
• 2 cloves garlic, minced
• 1 teaspoon fresh thyme (or ½ teaspoon dried)
• Salt and black pepper, to taste
• 1 cup Gruyère cheese, freshly grated
• ¼ cup heavy cream
• 1 large egg
• 1 tablespoon Dijon mustard
• Fresh thyme leaves or parsley, for garnish

Instructions

1. Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
2. Lightly roll out the puff pastry and place it on the baking sheet. Score a 1-inch border around the edges, being careful not to cut all the way through.
3. Heat olive oil and butter in a skillet over medium heat.
4. Add the mushrooms and cook for 8–10 minutes, until softened and lightly browned.
5. Stir in the garlic, thyme, salt, and black pepper. Cook for 30 seconds, then remove from heat.
6. In a small bowl, whisk together the egg, heavy cream, and Dijon mustard until smooth.
7. Spread the mushroom mixture evenly inside the scored pastry border.
8. Sprinkle the Gruyère cheese over the mushrooms, then drizzle the cream mixture evenly on top.
9. Bake for 25–30 minutes, until the pastry is puffed and golden and the filling is bubbly.
10. Garnish with fresh thyme or parsley, slice, and serve warm.

Variations

• Add caramelized onions for extra sweetness and depth.
• Substitute Gruyère with Fontina or Comté for a slightly different flavor profile.
• Include a handful of sautéed spinach for a greener version.
• Finish with shaved Parmesan just before serving for added sharpness.

Tips

• Sauté mushrooms until their moisture has fully cooked off to prevent a soggy tart.
• Use freshly grated cheese for the smoothest melt and best flavor.
• An egg wash on the pastry edges creates a deeper golden finish.
• This tart can be baked slightly ahead and reheated gently before serving.