1. Slice the onions thinly and peel and chunk the russet potatoes so everything is ready before you start cooking.

2. In a large skillet over medium low heat add 1 tablespoon of butter and the olive oil then stir in the sliced onions with a pinch of salt.

3. Cook the onions slowly for 15 to 20 minutes stirring occasionally until they are very soft and lightly golden adjusting the heat down if they brown too quickly.

4. While the onions cook place the potato chunks in a large pot and cover with cold water by about an inch then season the water generously with salt.

5. Bring the pot to a boil then reduce to a gentle simmer and cook the potatoes for 15 to 20 minutes or until they are very tender when pierced with a fork.

6. Before draining the potatoes scoop out about 0.25 cup to 0.5 cup of the starchy cooking water and set it aside then drain the potatoes well.

7. Return the drained potatoes to the hot pot and let them sit for 1 to 2 minutes so excess moisture can steam off.

8. In a small saucepan or microwave safe measuring cup combine the remaining 2 tablespoons butter heavy cream whole milk sour cream minced garlic 1.5 teaspoons salt and 0.5 teaspoon pepper.

9. Warm the dairy mixture gently over low heat or in the microwave until the butter melts and the mixture is hot but not boiling.

10. Mash the potatoes with a masher ricer or hand mixer on low while slowly pouring in the warm dairy mixture until the potatoes become smooth and creamy.

11. If the potatoes seem too thick stir in a splash of the reserved potato cooking water a little at a time until you reach your desired texture.

12. Gently fold the soft golden onions into the mashed potatoes until they are evenly distributed.

13. Taste and adjust the seasoning with more salt and pepper if needed.

14. Transfer the Smooth Onion Mashed Potatoes to a warm serving bowl and top with chopped fresh parsley and an extra pat of butter if you like.