Preheat the oven to 400° F. Carefully remove the stems from the mushrooms by twisting and pulling gently. Set half the stems aside (roughly chop) and discard the rest. Place the mushroom caps stem side down on a baking sheet and bake for 10-15 minutes to allow the water to drain. Soak up any additional moisture with paper towels.
While the mushrooms are baking, heat a large non-stick skillet on medium heat with 1 tbsp of olive oil. Add the panko to the pan, tossing to coat in olive oil, then arrange in a flat layer and toast for 2-3 minutes. Stir and toast for 2-3 minutes until golden brown. Transfer the toasted panko to a small bowl or plate, mix with chives, and set aside.
In the same pan you used for the panko, heat 1 tbsp of olive oil and sauté the onion, garlic, and mushroom stems until they begin to soften. Add the white wine and continue cooking until it's completely cooked down. Remove from heat, stir in the lemon juice, and set aside to cool completely.
When the onions and mushrooms have completely cooled, add them to a food processor with the whipped cream cheese and blue cheese. Pulse for 2-3 minutes until smooth and creamy.
Spoon the filling into each mushroom and bake at 375° F for 5 minutes. Top with toasted panko and serve warm.