Stuffed White Mushrooms with Pecan Breadcrumbs

Name: Stuffed White Mushrooms with Pecan Breadcrumbs
Ingredients: 2 1/2 pounds large white mushrooms, stemmed; 4 tablespoons extra-virgin olive oil; 1 medium red onion, finely diced; Kosher salt and freshly ground black pepper; 6 medium cloves garlic, grated; 1/2 cup dry white wine; 1/2 cup sour cream; 1 tablespoon fresh thyme leaves; 2 tablespoons unsalted butter; 1 tablespoon unsalted butter; 1 tablespoon extra-virgin olive oil; 1 cup panko breadcrumbs, toasted; 1/2 cup pecans, coarsely chopped, toasted; Kosher salt