Tomato Gratin

Tomato Gratin

A tomato gratin is one of the simplest things you can make with good summer tomatoes. Sliced tomatoes go into a baking dish, are drizzled with olive oil and covered with fresh parsley, basil, garlic, herbes de Provence, and finely grated Pecorino Romano, then go into a hot oven until golden and bubbling.

It's simple enough for any night of the week yet right at home at a summer gathering as well.

Why You'll Love This Baked Tomato Gratin

• A topping that goes beyond breadcrumbs. Fresh parsley, basil, garlic, Pecorino Romano, and herbes de Provence give this gratin a Mediterranean flavor.
• Simple to put together. Slice the tomatoes, mix the topping, assemble, and bake.
• Gluten-free. Almond flour replaces the breadcrumbs with no special substitutions needed.
• A versatile side. It pairs with almost anything and is elegant enough to serve to guests.

What Kind of Tomatoes to Use for a Tomato Gratin

Ripe, flavorful tomatoes are the most important ingredient in a baked tomato gratin. The oven concentrates and intensifies whatever flavor is already there, so the better the tomato, the better the result.

Vine-ripe tomatoes are the most reliable everyday choice. Large beefsteak tomatoes work and are easy to slice evenly. Roma tomatoes are a good option since they have a lower water content. Halved cherry tomatoes can also be used and give a slightly sweeter result.

Ingredients for Tomato Gratin

(Full quantities in the recipe card below.)

• Tomatoes — Ripe and flavorful. See the note above for variety recommendations.
• Extra virgin olive oil — For drizzling over the tomatoes and mixing into the topping. Use a good quality oil.
• Blanched almond flour — The gluten-free alternative to breadcrumbs. It gives the topping a golden crust with a subtle nuttiness. Use blanched almond flour, not almond meal, for the best texture. Gluten-free breadcrumbs work equally well if you prefer a more traditional result.
• Pecorino Romano — Finely grated. Its sharp, salty flavor is a good match for the sweetness of the tomatoes. Parmesan works as a substitute as well
• Fresh flat leaf parsley — Finely chopped.
• Fresh basil — Finely chopped. Pairs naturally with tomatoes.
• Garlic — Finely minced or grated.
• Herbes de Provence — A blend of dried herbs including thyme, rosemary, oregano, savory, fennel, and lavender that gives the topping its Provençal character. See the FAQ for substitution options.
• Fine sea salt and black pepper — To season the tomatoes and the topping.

How to Make Tomato Gratin

Step 1: Prep the tomatoes

Preheat the oven to 400°F / 200°C. Slice the tomatoes into rounds. Salt if necessary (see recipe notes below) and drain and pat dry.

Step 2: Make the topping

In a bowl, combine the almond flour, finely grated Pecorino Romano, chopped parsley, chopped basil, minced garlic, herbes de Provence, a drizzle of olive oil, salt, and pepper. Mix well until the mixture resembles coarse crumbs.

The topping should hold together slightly when pressed but still be crumbly. If it seems dry, add a little more olive oil.

Step 3: Assemble

Lightly oil a gratin dish or shallow baking dish. Arrange the tomato slices in overlapping rows, slightly shingled. Season with salt and pepper and drizzle with olive oil. Scatter the topping evenly over the tomatoes.

Step 4: Bake

Bake for 20 to 25 minutes until the topping is golden and the tomatoes are tender and bubbling around the edges.

Keep an eye on the topping in the last few minutes. Almond flour browns faster than breadcrumbs. If it's browning too quickly, tent loosely with foil.

Step 5: Rest and serve

Let the gratin rest for 5 minutes before serving. Serve warm or at room temperature, straight from the baking dish.

Tips for the Best Tomato Gratin Recipe

• Use the ripest tomatoes you can find. The oven intensifies whatever flavor is already there. Ripe, flavorful tomatoes produce a much better result than underripe ones.
• Watch the topping. Almond flour browns more quickly than traditional breadcrumbs. Check the gratin at the 20-minute mark and tent with foil if the topping is browning faster than the tomatoes are cooking.
• Don't skip the rest time. Let the gratin sit for at least 5 minutes before serving. It firms up slightly and the flavors settle.
• If your tomatoes are very juicy, sprinkle the slices with salt and let them drain in a colander for 20 minutes before assembling. Pat dry before using.

Variations

• Use Parmesan instead of Pecorino. Parmesan is milder and slightly less salty.
• Use gluten-free breadcrumbs. If you prefer a more traditional crunch, swap the almond flour for an equal amount of gluten-free breadcrumbs.
• Try different herbs. Thyme and oregano work well in place of or alongside the parsley and basil. A small amount of fresh rosemary is also a good addition.
• Add olives. A scattering of finely chopped black olives over the tomatoes before adding the topping works beautifully with the Provençal herbs.

How to Serve Tomato Gratin

As a side dish: This dish fits alongside any French or Mediterranean-style meal.

How to Store Tomato Gratin

Refrigerator: Store covered in the fridge for up to 2 days. Reheat in a low oven at 325°F / 165°C until warmed through.

Freezer: This gratin doesn't freeze well.

FAQ

Can I make this tomato gratin ahead of time?
You can assemble the gratin a few hours ahead and keep it covered in the fridge. Bake just before serving for the best topping texture. Fully baked leftovers reheat well in a low oven.

Can I use regular breadcrumbs instead of almond flour?
Yes, if gluten isn't a concern. Use an equal amount of fresh breadcrumbs or gluten-free breadcrumbs. The texture will be slightly crispier and the flavor more neutral. The almond flour gives the topping a nuttier character that works well with the Provençal herbs and Pecorino.

What is herbes de Provence?
Herbes de Provence is a French dried herb blend typically containing thyme, rosemary, savory, oregano, marjoram, fennel, and lavender. It's widely available in supermarkets and gives this topping its distinctly Provençal character. If you can't find it use dried thyme as a substitute.

Can I make this tomato gratin dairy-free?
Yes. Omit the Pecorino Romano and add a tablespoon of nutritional yeast to the topping in its place.

Final Thoughts

There's a reason dishes like this have been made in the south of France for generations. The ingredients are simple, the technique is easy, and good ingredients do the rest. I hope you enjoy it.

More Tomato Side Dishes

• Marinated Tomatoes
• Garlic Roasted Tomatoes
• Provencal Tomatoes