Preheat oven to 375°F (190°C). Line a large baking sheet with parchment paper. Clean mushrooms with a damp paper towel (never submerge in water). Gently pop out the stems; finely dice the stems and set aside. Toss mushroom caps lightly with 1 tablespoon olive oil and a pinch of salt; arrange cavity-side up on the baking sheet.

Heat 1 tablespoon olive oil in a skillet over medium heat. Add the halal beef sausage and cook for 5 to 6 minutes, breaking it into fine crumbles with a wooden spoon, until browned. Transfer sausage to a paper towel-lined plate.

In the same skillet with remaining drippings, add the finely diced mushroom stems and minced onion. Sauté for 4 minutes until all released moisture evaporates. Add minced garlic and cook for 60 seconds until fragrant. Remove from heat and let cool for 5 minutes.

In a mixing bowl, combine the softened cream cheese, cooked sausage, sautéed mushroom-onion mixture, 1/4 cup grated parmesan, chopped parsley, and black pepper. Stir until thoroughly combined and creamy.

Use a small cookie scoop or spoon to mound a generous tablespoon of filling into each prepared mushroom cap, pressing gently to compact.

In a small bowl, toss panko breadcrumbs with melted butter and the remaining 1/4 cup grated parmesan. Sprinkle breadcrumb mixture generously over the tops of each stuffed mushroom.

Bake at 375°F (190°C) for 18 to 20 minutes, until the mushroom caps are tender and juicy and the breadcrumb topping is deeply golden-brown and crisp.

Remove from oven and let rest for 5 minutes so juices settle. Garnish with fresh chopped parsley and flaky sea salt. Serve warm straight from the platter!