In a medium sized microwave safe bowl, add the ½ cup dry white wine, 4 Tbsp butter, 2 cloves minced garlic, 2 tsp brown sugar, and 1 tsp chopped fresh rosemary. Microwave in 30 second increments until butter is melted then give the mixture a quick stir.
Lay the two chicken breasts in a 8" x 8" pan. Brush the butter sauce liberally over each chicken breast and then season each with salt and pepper.
Top each chicken breast with a layer of chopped pecans, pressing your hand over them to make sure they adhere. Top with any remaining pecans (it's fine to pile them up a bit).
Bake the chicken at 375° for 30-35 minutes or until cooked through.
Add the ½ cup heavy cream, ½ cup milk, ¼ cup dry white wine, ¼ tsp salt, and ⅛ tsp pepper to a small sauce pan. Bring the ingredients to a boil over medium-high heat. Cook, stirring occasionally until the sauce thickens and reduces by one third.
Reduce the heat to low and stir in half of the ⅓ cup of blue cheese. For a chunkier sauce reserve the second half, for a smoother sauce, add the entire ⅓ cup here. Cook and stir an additional few more minutes until cheese is melted and incorporated. Remove from the heat. For a chunky sauce, add in the reserved half of the blue cheese and stir to combine.
Serve chicken warm from the oven, and drizzle with the blue cheese sauce.