Mashed Sweet Potatoes with Pecans

INGREDIENTS

1 1/4 lb

russet potatoes (about 2 medium), peeled and chopped

1 1/4 lb

sweet potatoes (about 2 medium), peeled and chopped

Kosher salt

cayenne pepper

1 1/2 sticks

salted butter, cut into pieces, at room temperature

1/4

to 1/2 cup milk, warmed

Freshly ground black pepper

1/3 cup

chopped pecans

to 2 teaspoons packed light brown sugar