Pierce each potato with a fork 3 to 4 times on each side. Wrap each potato in a damp paper towel. Microwave at HIGH 8 minutes, turning after 4 minutes. (NOTE: My sweet potatoes took much longer to cook in the microwave. Closer to 20 minutes. Check with a fork every 10 minutes until sweet potatoes are cooked through) Cool slightly. Cut potatoes in half; scoop pulp into a bowl. Mash pulp.
Heat butter in a small saucepan over medium heat; cook 3 minutes or until browned. Stir butter, milk, and salt into potato pulp. Top with pecans.