Place potatoes and 1 tablespoon salt in large saucepan, add water to cover by 1 inch; bring to boil over high heat. Reduce heat to medium and simmer until potatoes are tender and paring knife can be easily slipped into and out of potatoes, 18 to 22 minutes.
Meanwhile, cook bacon in 10-inch skillet over medium heat until crispy, 5 to 7 minutes. Using slotted spoon, transfer bacon to paper towel–lined plate. Combine half-and-half and butter in 2-cup liquid measuring cup and microwave, covered, until butter is melted and mixture is warm to touch, about 2 minutes.
Drain potatoes and return them to saucepan. Using potato masher, mash potatoes until smooth and no lumps remain. Stir in half-and-half mixture, pepper and salt just until fully combined. Stir in cheddar, sour cream, chives and bacon until incorporated; try not to overwork.