Preheat your oven to 180°C (350°F). Gently brush the mushroom caps clean and remove their stems, setting the caps aside and chopping the stems finely.
Toast the breadcrumbs in a dry skillet over medium heat until golden and crispy, then set aside to cool.
Heat a tablespoon of olive oil in a skillet over medium heat, then add the chopped mushroom stems and minced garlic. Sauté until fragrant and slightly browned, about 3-4 minutes. Let this mixture cool slightly.
In a mixing bowl, combine the sautéed stems and garlic with cream cheese, chopped parsley, thyme, lemon juice, and half of the toasted breadcrumbs. Mix until smooth and season with salt and pepper to taste.
Using a small spoon or piping bag, generously fill each mushroom cap with the prepared mixture, pressing gently to fill the cavity completely.
Arrange the stuffed mushrooms on a parchment-lined baking sheet. Drizzle a little olive oil over the tops and sprinkle the remaining breadcrumbs for added crunch.
Bake in the preheated oven for 20-25 minutes, until the filling is bubbling and the tops are golden brown. The mushroom caps should be tender and juicy.
Remove from the oven and let rest for 5 minutes. Garnish with extra herbs if desired, then serve warm for best flavor and texture.