Melt 2 tbsp (30 mL) butter; set aside. In large bowl, whisk flour with baking powder, baking soda, ginger, cinnamon, salt and cloves. In another bowl, whisk eggs with buttermilk, melted butter, sweet potatoes, 1 tbsp (15 mL) maple syrup and molasses. Stir wet ingredients into dry ingredients just until moistened (it’s fine if batter is slightly lumpy). Let batter stand 15 min., or cover and refrigerate up to 1 hr.
Preheat large, non-stick skillet or griddle over medium heat. Brush skillet with some of the oil. In batches, pour scant ¼ cup (60 mL) batter per pancake into skillet, spacing out pancakes to allow for spreading. Cook 3 to 5 min., until bubbles form on surface. Flip and cook 1 to 2 min. until bottom is golden. Wipe skillet between batches and brush with more oil as needed. Make 16 pancakes.
Meanwhile, heat remaining maple syrup over medium-low heat for 10 min. until it starts to simmer. Remove from heat and stir in remaining butter just before serving. Serve pancakes with warmed maple syrup. Sprinkle with pecans, if using.
To get 1 cup (250 mL) mashed sweet potatoes, prick large sweet potato (about 12 oz/375 g) all over with fork. Microwave on HIGH 5 to 7 min., turning once, until tender. Scoop out flesh and mash.