Kale Tarts with Fennel and Olives

Name: Kale Tarts with Fennel and Olives
Ingredients: 2 tbsp. extra-virgin olive oil, plus more for drizzling; 1 medium yellow onion, diced (1 cup); 1 medium bulb fennel, quartered, cored, and thinly sliced (3.4 cup); 3 cloves garlic, finely chopped (1 Tbsp.); 1 medium bunch Lacinato kale, stems removed, chopped into bite-sized pieces (6 cups); 1⁄3 cup crumbled feta cheese, plus more for topping; 1⁄4 cup kalamata olives, pitted and finely chopped; 2 tbsp. coarsely chopped fresh parsley; Fresh ground black pepper; 1 (17-oz.) package (2 sheets) all butter puff pastry, thawed in the fridge overnight; 3 tbsp. unsalted butter, melted