Apple and Onion Confit Crostini

Name: Apple and Onion Confit Crostini
Ingredients: 2 tablespoons unsalted butter, at room temperature; 2 tablespoons extra-virgin olive oil; 1 large onion, thinly sliced; 1 green apple, such as Granny Smith, unpeeled, cored, and thinly sliced; 1 red apple, such as Washington, unpeeled, cored, and thinly sliced; 1/2 teaspoon kosher salt; 1/4 teaspoon freshly ground black pepper; 1/4 cup apple cider vinegar; 2 tablespoons maple syrup; 1 tablespoon chopped fresh thyme leaves; 1 French baguette, thinly sliced into 26 (1/4 to 1/2-inch thick) slices; Extra-virgin olive oil, for drizzling; 3 ounces creamy gorgonzola cheese sliced into 26 (1/4-inch thick) 1-inch squares