What I do:
Preheat oven to 400.
Set water to boil.
Cut a small potato into small cubes.
Cut mushrooms (and/or any other vegetables) into small, uneven chunks
Chop at least two garlic cloves
Salt boiling water and add two handfuls of (twisty) pasta
Butter small ovenware
Add potato cubes to cooking pasta OR mix with oil and put in oven in buttered ovenware
Cooked pasta+chopped veggies+garlic into same ovenware with potatoes
Salt and pepper well (sometimes I add some cayenne pepper)
Add shredded cheese and mix well
Back into oven for about 7 minutes
Add more shredded cheese to cover the top
Back into oven for about 5-7 minutes (until cheese is all melted on top)