Heat Dutch oven or heavy pot to medium.
Add oil, butter, mushrooms, garlic, marjoram, salt, and pepper. Stir and cook 5 minutes, uncovered.
Add lemon juice and zest and cook 5 minutes uncovered (reducing the liquid).
Add rice, and cook 1 minute, stirring.
Add stock/broth and turn up heat. Heat to almost boiling, stirring frequently (about 2 minutes).
Turn heat back down to medium and cook for 10 minutes, stirring continuously to make sure rice doesn't stick to pan bottom.
Turn heat to low-medium (2-3) and cook 5 more minutes, stirring frequently.
Remove from heat, add cream and parmesan cheese, and stir.
Cover and let sit 5 minutes. Stir again before serving.