While the sweet potatoes are cooking, add the 1/2 cup of butter + the 1/3 cup butter to a saucepan over medium heat. Once melted the butter will foam up a bit and you'll see brown specks form at the bottom. It should have a nutty aroma. Pour in a bowl to stop the butter from cooking.

Preheat oven to 350. Peel the skin off of the potatoes, and add them to a mixing bowl and mash the potatoes. Add the 1/2 cup of brown butter (make sure to get the brown bits) brown sugar, granulated sugar, milk, vanilla bean paste, nutmeg, salt & cinnamon. Mix until well combined.

Pour in beaten egg and mix.
Pour the sweet potato mixture to a casserole dish, I used a 9x13.

In a seperate bowl combine brown sugar, pecans, flour & 1/3 cup brown butter (make sure to get the brown bits). Stir to combine. Sprinkle the topping evenly over the top, and bake for 35- 40 mins or until golden brown.