Preheat the oven to 400F, and fit a muffin tin with liners.

In a small nonstick pot, combine the diced pears, white sugar, cinnamon, and water, and heat to medium.

Stir occasionally, until the sugar melts and thickens, and the pears soften. Turn off heat and set aside to cool.

In a separate small pot {preferably not nonstick}, brown the butter. To do this, melt the stick of butter over medium-low heat, whisking constantly. Allow the butter to bubble and boil, and keep whisking until tiny brown flecks start to form at the bottom, and the butter smells nutty. Immediately remove from heat, and let cool.

In a large bowl, beat together the eggs and white and brown sugars.

Pour in the cooled browned butter, along with the vanilla, cinnamon, and sour cream, and whisk to combine.

Switch to a spatula or spoon, and add in the flour, baking soda, and salt, mixing until JUST combined.

Pour in the caramelized pears, along with any liquid that might be in the pot, and lightly mix.

Divide the batter evenly among 12 muffins, then bake for 20-22 minutes, until the tops are golden brown and a toothpick comes out with just a couple of crumbs.