Portobello Baked Eggs

Name: Portobello Baked Eggs
Prep time: 13 min
Cook time: 14 min
Ingredients: 4 medium portobello caps (4 to 5 oz each), stems and dark gills removed; 1 tbsp olive oil; 1 small clove garlic, grated; 1/2 cup shredded low-moisture mozzarella; 4 large eggs; 1/4 tsp kosher salt, divided; Black pepper; 2 tbsp finely grated Parmesan; 1 tbsp fresh chives, sliced thin

⏲ ~27 min total · prep 13 · cook 14 · 4 servings

Breakfast⏱ 30 min total🔥 3.0g net carbs⚡ ≈647 kcal/serving~5% of calories from carbs

By the KFI Test Kitchen · Tested & approved by Jason Lieu, KFI recipe editor

Published Sep 15, 2026 · Updated Sep 15, 2026

Ingredients

4 medium portobello caps (4 to 5 oz each), stems and dark gills removed
1 tbsp olive oil
1 small clove garlic, grated
1/2 cup shredded low-moisture mozzarella
4 large eggs
1/4 tsp kosher salt, divided
Black pepper
2 tbsp finely grated Parmesan
1 tbsp fresh chives, sliced thin

Instructions

Heat the oven to 400°F and brush a rimmed 9x13-inch baking dish with a little of the olive oil.
Rub the caps all over with the remaining oil, the grated garlic, and half the salt, then arrange them gill-side up in the dish.
Roast 8 minutes gill-side up, flip each cap over, and roast 4 minutes more — this pre-roast drives out the water that would otherwise flood your eggs.
Blot the cavities dry with a paper towel, lower the oven to 375°F, and divide the mozzarella among the caps.
Crack one egg into each cap, season with the remaining salt and a grind of pepper, and return the dish to the oven.
Bake 12 to 15 minutes, until the whites are fully opaque and set but the yolks still wobble when you nudge a cap.
Shower with the Parmesan and chives and rest 3 minutes — the yolks come out molten and boiling-hot.

Why this recipe works

The pre-roast Eight minutes gill-side up and four minutes flipped drives the water out of the caps first, so the eggs bake in a mushroom instead of a puddle.
One cap, one egg Each 4 to 5 ounce cap holds exactly one egg over its mozzarella lining, which makes portions automatic.
Low-moisture mozzarella Shredded low-moisture mozzarella melts into a base under the egg without releasing the water fresh mozzarella would.

Tips for making this recipe well

Remove the gills

Scrape the dark gills out with a spoon before oiling the caps. They can taste muddy and they stain the egg gray.

Blot the cavities

Press a paper towel into each cap after the pre-roast to pick up the water that cooked out. Skip the blot and the egg slides around in dilute mushroom broth.

Nudge to check

At 12 minutes, nudge a cap. Set whites hold still while the yolk wobbles beneath, and that wobble is the moment to pull the dish.

Respect the rest

The yolks come out molten and boiling hot. Three minutes on the counter settles them enough to eat without scalding anyone.

Serving suggestions

Serve one cap per plate with the Parmesan and sliced chives scattered over, and hand everyone a knife; breaking the yolk into the cavity is the point of the dish. At 3 net carbs a serving, two caps make a full breakfast, and the roasting dish can go straight to the middle of a brunch table family-style. The caps hold their shape, so no special plating is required.

Storage and meal prep

These are made for right now, while the yolk still runs; a firm yolk in a portobello is a different, drier meal. If you have extras, refrigerate them up to 3 to 4 days and warm gently in a 350°F oven. The make-ahead move is the pre-roast: roasted, blotted caps hold a day in the refrigerator and take the eggs at dinner with only the second bake to wait for.

Variations worth trying

Sausage layer A small spoon of cooked crumbled sausage under the egg in each cap.
Spinach underneath A few leaves of wilted, squeezed-dry spinach tucked in under the mozzarella.
Change the finish Thyme leaves or torn basil stand in for the chives on top.

Frequently asked questions

Why pre-roast the mushrooms?

Portobellos release a surprising amount of water. The two-stage roast at 400°F drives it out first, so the eggs bake in a dry cavity instead of diluting into broth.

Can I crack the eggs ahead of time?

No, crack them right before the dish returns to the oven. Eggs that sit in the cavities weep and set unevenly.

How do I know the eggs are done?

Whites fully opaque and set, yolks still wobbling when you nudge a cap, usually 12 to 15 minutes at 375°F. The 3-minute rest finishes the job off the heat.

Do I have to remove the gills?

They are edible, but scraping them out gives the eggs a cleaner look and taste. A spoon does the job in seconds per cap.

Can I make this for a crowd?

Yes, the recipe scales across more caps in the same 9x13 dish, and everyone gets an identical portion. The pre-roast can happen before anyone arrives.

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