In a large stockpot, heat oil and saute onion for 5 to 7 min over low to med heat.

Add potatoes, broccoli and stock. Bring to a boil.

Reduce to simmer and cook covered for 12 to 15 min under broccoli and potatoes are tender.

Remove from stove , allow to cool a bit.

Pour mixture and cheese into blender; puree.