Combine butter, cream, salt, sugar, and sweet potatoes in 3 to 4 quart saucepan; cook, covered, over low heat, stirring occasionally, until potatoes fall apart when poked with fork, 35 to 45 minutes. I like them really soft so they mash well.
Off heat, mash sweet potatoes in saucepan with potato masher if you want them a little chunkier. For more pureed potatoes, use a stick blender or food processor. Stir in pepper, maple syrup, and orange zest; serve immediately.
Place a nonstick griddle or 12-inch nonstick frying pan over medium heat (350F); when hot, coat lightly with butter; wipe excess butter off with a paper towel. Adjust heat to maintain temperature.
In a large bowl, stir together flour, brown sugar, baking powder, baking soda and salt. In another large bowl, whisk the egg, then whisk in mashed sweet potatoes, yogurt (or sour cream) and butter until well blended. Gradually whisk in milk. Stir flour mixture into egg mixture just until evenly moistened.
Spoon batter (use a #24 scoop) onto griddle and gently spread into 3-inch rounds. Cook until pancakes are browned on the bottom and edges begin to look dry, 2-3 minutes; turn with a wide spatula and brown other side, 2-3 minutes longer. As pancakes are cooked, transfer to baking sheets and keep warm in a 200 degree oven. Serve warm with Orange Syrup.
Combine the sugar and water in a small saucepan. Bring to a boil; stir until sugar has dissolved; reduce heat to medium.
Combine juice and cornstarch in a bowl; pour into sugar syrup. Simmer gently until thick, 6 to 8 minutes, stirring very frequently. Add butter and orange zest; stir until it melts. Serve warm.