I did them last night in the microwave....WOW were they good! I used my Mandoline for the potatoes (did not peel then) and onion. Put in DCB, added salt & peper. In sauce pan I melted 3T butter, added 3T flour until thick, added 2 cups milk and kept stirring until thick. Then used coarse grater and added to milk mixture 1 1/2 cups grated cheddar cheese. Stirred this until cheeese melted (wasn't long). Poured cheese mixture over potatoes/onion. Covered and put in microwave for 30 minutes (actually did 3 x @ 10 min each).