Using mandolin, slice potatoes and place in 11x13 baking dish or pan.
Mince onion finely and scatter throughout the potatoes. Add as much garlic as you want. I tend to use a heaping tbs of the jarred minced garlic. lay a few pats of butter or margarine on top of the potatoes/onion mixture.
Next cut kielbasa into bite-size pieces and completely cover the bottom layer. You may have to overlap some of the pieces.
Cover with foil and bake for 45 minutes.
After 30 minutes, remove foil and continue baking.