Cookout Companion Bake: Just 4 ingredients. I assemble it early when I want a stress-free addition to the picnic table.

This 4-ingredient umami bake is my go-to “cookout companion” when I want something stress-free that still looks like I fussed. It’s basically a layered, cheesy mushroom bake that goes into the oven pale and simple, then comes out with a glistening, deeply savory layer and a charred, bubbling top. I usually assemble it in the morning before work or a weekend barbecue, stash it in the fridge, then just bake it off right before we head out or while burgers are on the grill. It feels a little nostalgic—kind of like those creamy potluck casseroles we grew up with in the Midwest, but slightly streamlined for busy weeknights and picnic-table life.

Serve this bake hot or warm alongside grilled burgers, brats, or barbecue chicken. It’s especially good with anything smoky because the umami-rich mushrooms and browned cheese play so nicely with char from the grill. Add a crisp green salad or simple coleslaw to balance the richness, and maybe a basket of crusty bread or buttered rolls to scoop up the creamy, roasted bits from the bottom of the dish. Leftovers are great spooned over baked potatoes or grilled steak the next day.

Servings: 6

24 oz sliced cremini or button mushrooms (about 680 g)

Lightly grease a 9x13-inch glass casserole dish so the mushrooms don’t stick and the edges can caramelize nicely.

Spread the sliced mushrooms evenly in the bottom of the glass dish. They should form a generous, slightly overlapping layer; they’ll shrink as they roast.

In a medium bowl, stir together the shredded mozzarella, 1/2 cup of the grated Parmesan, and the bottled umami-rich sauce until everything is evenly coated and looks like a thick, saucy cheese mixture.

Spoon the saucy cheese mixture over the mushrooms, then use the back of the spoon to spread it into an even layer, making sure the mushrooms are mostly covered. This helps them steam and roast underneath while the top bubbles and chars.

Sprinkle the remaining 1/2 cup grated Parmesan evenly over the top. This extra layer is what helps create that deeply golden, almost charred, bubbling crust.

If you’re assembling ahead for a picnic or cookout, cover the dish tightly with foil or a lid and refrigerate for up to 24 hours. When you’re ready to bake, let it sit at room temperature for about 20–30 minutes while the oven preheats, so the glass dish doesn’t go from very cold to very hot too fast.

When ready to cook, preheat your oven to 400°F (200°C). Uncover the casserole and place it on the middle rack.

Bake for 25–30 minutes, until the mushrooms are releasing their juices and the cheese layer is fully melted and bubbling around the edges.

Turn the oven to broil (high, if you have the option) and broil for 2–5 minutes, watching closely, until the top is deeply golden, glistening, and has some charred, bubbly spots. Rotate the dish once under the broiler if your oven browns unevenly.

Carefully remove the glass dish from the oven and let the bake rest for at least 10 minutes. The bubbling top will settle, the sauce will thicken slightly, and the roasted mushrooms underneath will be easier to scoop without sliding everywhere.

Serve straight from the glass dish with a big spoon, making sure each portion gets some of the roasted mushroom base and the charred, umami-rich cheese top.

You can tweak this bake a bit depending on what you have on hand or who you’re feeding. For a smokier flavor, use a smoky steak sauce or a thick teriyaki-style glaze with a splash of liquid smoke. If you like a sharper bite, swap part of the mozzarella for provolone or a sharp white cheddar (just keep the total shredded cheese amount the same). To stretch the dish for a bigger crowd, add an extra 8 oz of mushrooms and increase the umami sauce by a few tablespoons so everything still looks well coated. If you need it vegetarian, just choose a vegetarian-friendly umami sauce (many steak-style sauces contain anchovies or Worcestershire). For a slightly lighter version, you can reduce the cheese by about 1/2 cup and add a few tablespoons of water or low-sodium broth to the sauce mixture so it still spreads easily over the mushrooms. Food safety tips: Keep the assembled, unbaked casserole refrigerated at or below 40°F (4°C) and bake within 24 hours. Don’t place a very cold glass dish directly into a hot oven; let it sit at room temperature for 20–30 minutes first to reduce the risk of the glass cracking. Bake until the center is hot and bubbling; if you’re unsure, you can check that the internal temperature has reached at least 165°F (74°C). Refrigerate leftovers within 2 hours of baking, store tightly covered, and enjoy within 3–4 days, reheating until steaming hot before serving.