Make the garlic crème fraîche at least 20 minutes ahead to let flavors meld. In a small bowl, combine 1 cup crème fraîche, 1 grated garlic clove, 1/2 tsp lemon zest, 1/2 tsp lemon juice, 1 tbsp chopped chives or parsley, 1/4 tsp salt and 1/4 tsp black pepper. Stir until smooth, taste and adjust seasoning. Cover and refrigerate.

Mushrooms & Finish

Prepare mushrooms

Clean the portobello mushrooms by wiping caps with a damp paper towel. Remove and discard stems; if desired, gently scrape out gills with a spoon for a cleaner presentation. Pat dry.

Season

In a small bowl, mix 3 tbs olive oil, 1 tbs melted butter, 3 minced garlic cloves, 1 tsp fresh thyme leaves, 1 tsp salt, 1 tsp freshly ground black pepper and 1 tsp lemon juice. Brush mixture all over both sides of the mushroom caps.

Cook

Heat a large skillet (preferably cast iron) over medium-high heat until hot. Add the mushrooms cap-side down and cook without moving for 4–5 minutes, until well browned. Flip and cook another 3–4 minutes, basting with remaining pan juices, until mushrooms are tender and glossy. If using oven, preheat to 200°C/400°F and roast on a tray cap-side down for 10–12 minutes.

Finish

Transfer mushrooms to a plate and allow to rest 1–2 minutes. Taste and adjust seasoning with extra salt, pepper or a light squeeze of lemon if desired.

Brioche & Plating

While mushrooms cook, heat a separate skillet over medium heat. Add 1 tbsp butter and toast brioche slices 1–2 minutes per side until golden and crisp. Alternatively, toast under a broiler for 1–2 minutes per side, watching closely.

To serve: Spread about 1–2 tbsp garlic crème fraîche onto each warm brioche slice. Place a cooked portobello mushroom on top of each slice. Spoon an additional small dollop of crème fraîche on the mushroom, sprinkle with chopped chives or microgreens, and drizzle with 1 tsp olive oil if using. Serve immediately.