Mashed potato add-ins

We love our potatoes both mashed and whipped, but when you're going to add a bunch of savory bits to them, lightly mashing them by hand seems the best way to go. 

Mashed Potatoes

4 large Russet potatoes, peeled
1/2 stick (4 T) butter
Salt and pepper
1 c half-and-half, warm

Add-ins:
4 - 5 T horseradish
3 - 4 scallions, sliced thin green and white parts

2 T brown mustard
3 - 4 oz smoked cheese like gouda

Boil the potatoes whole and then simmer until tender, about 20 minutes.  Drain and return the potatoes to the warm pan to dry out slightly.  Cut the butter into pieces and mash it into the potatoes to melt, along with the salt and pepper.  Chose one of the add-in groups to mix with the warm half-and-half. and mash it all into the potatoes.  Keep warm until time to serve.