Step 1: Preheat the oven

Preheat your oven to 375°F (190°C).

Lightly coat a large baking sheet with nonstick cooking spray. This will help prevent the mushrooms from sticking during baking.

Step 2: Prepare the mushrooms

Remove the stems from the portobello mushroom caps and finely chop them. Set the chopped stems aside for the filling.

Using a small spoon, gently scrape out the dark gills from the underside of each mushroom cap.

Wipe the mushrooms clean with a slightly damp paper towel, removing any visible dirt.

Avoid soaking the mushrooms in water because they can absorb excess moisture.

Step 3: Pre-bake the mushroom caps

Arrange the prepared portobello caps on the baking sheet with their hollow sides facing upward.

Season lightly with salt and freshly ground black pepper.

Place the baking sheet in the preheated oven and bake for 8 minutes.

Carefully remove the mushrooms from the oven. Use paper towels to blot away any liquid that has collected inside the caps.

Set the mushrooms aside while preparing the filling.

Step 4: Combine the crab filling

In a medium mixing bowl, combine the chopped mushroom stems, lump crabmeat, panko breadcrumbs, sweet onion, minced garlic, thyme, lemon juice, and all but 2 tablespoons of the shredded cheese.

Season lightly with salt and black pepper.

Gently fold the ingredients together until evenly distributed.

Take care not to break up the crabmeat too much. Keeping some larger pieces intact gives the finished filling a more satisfying texture.

Step 5: Add the beaten egg

Pour the lightly beaten egg into the crab mixture.

Fold gently until the ingredients are just combined and the filling begins to hold together.

Avoid overmixing, which can make the filling dense and break apart the delicate crab pieces.

Step 6: Fill the portobello caps

Divide the prepared crab filling evenly among the four mushroom caps.

Gently press the mixture into each cap, allowing the filling to mound slightly above the edges.

Make sure the filling is evenly distributed so the mushrooms cook consistently.

Step 7: Bake the stuffed mushrooms

Return the baking sheet to the oven.

Bake for 10–12 minutes, or until the filling is set, heated through, and lightly golden around the edges.

The mushroom caps should be tender, and the crab filling should smell fragrant and savory.

At this stage, your Baked Crab Stuffed Portobello Mushrooms are almost ready to serve.

Step 8: Add the cheese topping

Remove the baking sheet from the oven and sprinkle the reserved 2 tablespoons of shredded cheese evenly over the stuffed mushrooms.

Return the mushrooms to the oven for another 2–4 minutes.

Continue baking until the cheese is completely melted and bubbly.

For food safety, check that the center of the egg-containing filling reaches 160°F (71°C).

Step 9: Serve warm

Allow the mushrooms to rest for 2–3 minutes before serving.

Carefully transfer them to individual plates and serve with fresh lemon wedges.

Add a little halal-friendly hot sauce if desired.

Enjoy while the mushrooms are warm and the cheese is beautifully melted.