Preheat oven to 350°F. Line a 12-cup muffin pan with paper cupcake liners.
Melt 4 tablespoons butter in a small bowl. Stir in brown sugar until it becomes a blended slurry. Divide mixture among paper cups. Sprinkle pecans on top of the mixture.
In a large bowl, cream together remaining 4 tablespoons butter and granulated sugar. Beat in eggs and yogurt.
Stir in flour, baking powder, baking soda, cinnamon, and salt until just blended.
Divide batter among paper cups. Bake for 18-20 minutes, until lightly browned.
Let cool in pan for 2 minutes, then remove and turn muffins over, carefully removing the paper liners. Scrape any stuck caramel or pecans off the liner and onto the muffin. Serve warm.