Preparation Method
Heat the griddle to 400°F. Place the mushroom caps, stem side down, on the griddle. Cover, and cook until golden brown on the bottom, 10 minutes. Flip mushroom caps over. Divide arugula, cheese, and red onion among mushroom caps. Season with salt and pepper. Cover the griddle, and cook stuffed mushrooms until tender and golden brown on the bottom and cheese is melted, 10 minutes more. Serve warm.
Variations
SPINACH-ARTICHOKE STUFFED MUSHROOMS
Make as directed. Substitute low-moisture mozzarella for Cheddar. Add 4 artichoke hearts (100 grams) from a can, roughly chopped, ½ cup (110 grams) frozen thawed spinach, squeezed dry, and 1 garlic clove (6 grams), minced, to filling.
FRENCH ONION STUFFED MUSHROOMS
Make as directed, omitting arugula and red onion. Substitute Gruyère cheese for Cheddar. Add ½ cup caramelized onions (120 grams) and 2 teaspoons (2 grams) fresh thyme leaves to filling.
Pro Tip
Look for relatively flat portobello mushroom caps, as they will cook quicker and be easier to fill than those with high sides.
