Mushroom, Spinach & Gruyere Recipe

Prepare mushrooms

Wipe mushrooms clean with a damp cloth and finely chop them. This should yield about 10 oz chopped mushrooms.

Heat a large skillet over medium-high heat. Add 1 tbsp olive oil and 1 tbsp butter until foaming.

Add the minced shallot and cook 1–2 minutes until softened and translucent, stirring frequently so it doesn't brown.

Add the chopped mushrooms in a single layer and let them sear undisturbed 2–3 minutes to release moisture, then stir and continue cooking 5–7 minutes until most liquid has evaporated and mushrooms are browned.

Add the minced garlic and thyme and cook 30–45 seconds until fragrant, taking care not to burn the garlic.

Add the chopped spinach in batches, stirring and allowing it to wilt between additions. Cook until all spinach is wilted and any excess moisture has mostly cooked off, about 2–3 minutes.

Season with 1 tsp salt, 1 tsp freshly ground black pepper and a pinch of freshly grated nutmeg (if using). Taste and adjust seasoning. Transfer the mixture to a colander or fine-mesh sieve and press gently with the back of a spoon to remove excess liquid. Let cool 5–10 minutes.

In a medium bowl, combine the softened cream cheese and the beaten egg, whisking until smooth and well combined.

Fold in the grated Gruyère and the optional Parmesan until evenly distributed.

Add the cooled mushroom-spinach mixture to the cheese mixture and stir until combined. If the filling seems too wet, squeeze a bit more liquid from the filling or add an extra tablespoon of grated Gruyère to help bind.

Taste the combined filling and adjust salt and pepper as needed.

Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.

Lightly flour your work surface. Unfold the thawed puff pastry sheet and, if making a tart, roll gently into a roughly 12 x 10-inch rectangle. If making turnovers or hand pies, cut into desired shapes (e.g., four squares).

If making a tart: transfer the pastry to the prepared baking sheet. Use a knife to lightly score a 1-inch border around the edge without cutting all the way through. Prick the center with a fork a few times to prevent excessive puffing.

Spread the mushroom-spinach-gruyère filling evenly inside the scored border (or mound about 2–3 tablespoons on each pastry square for hand pies).

If making turnovers or hand pies: fold, seal, and crimp edges with a fork. Brush edges with a little beaten egg to help seal, if needed.

Make the egg wash by whisking the egg yolk with 1 tsp milk. Brush the pastry edges and top lightly with the egg wash for a golden finish. Optionally brush with 1 tsp olive oil or melted butter for extra sheen and flavor.

Bake in the preheated oven for 18–22 minutes (tart) or 15–18 minutes (smaller hand pies) until the pastry is puffed and golden and cheese is melted and bubbling.

Remove from oven and let cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool another 5–10 minutes. Serve warm or at room temperature.

Slice the tart into 6–8 pieces or serve two hand pies per person as an appetizer. Garnish with extra thyme leaves or a light sprinkle of grated Parmesan if desired.