Add the butter to a large rondeau pot over low heat until melted.
Next, add the onions and cook until very well caramelized, which will take about 35-40 minutes. Stir every 5-6 minutes.
After about 20-25 minutes of the onions caramelizing, add in the leeks and garlic and cook for a further 10-15 minutes.
Deglaze with some white wine and cook until it is au sec, or almost gone. There should be a bout 1 to 2 tablespoons of wine left.
Add in the carrots and celery and sweat the vegetables on low to medium heat for 3-4 minutes.
Place in the potatoes and then immediately pour in the chicken stock and heavy cream.
Slowly sprinkle in the flour while continuing to whisk until it is completely mixed in. I cannot stress this enough, whisk very well.
Turn the heat to high and bring it to a boil, which will take about 10-15 minutes after you are done whisking.
Once the soup is very thick, add in the ham, salt, pepper, tabasco, Worcestershire sauce, and parsley, and mix in until combined.
Serve the soup and garnish with crème fraiche, or sour cream, and chopped chives or sliced green onions.
Notes
Make-Ahead: You can make this recipe up to 1 to 2 days ahead of time, just heat up before serving.How to Store: Cover and keep in the refrigerator for up to 5 days. Cover and freeze for up to 3 months. Thaw in the refrigerator before reheating and serving.How to Reheat: Add the desired amount of ham and potato soup to a medium-size pot and heat over low heat until hot.You can substitute the yellow onion for a sweet or white onion.Substitute the russet potatoes for Yukon gold or red potatoes.Feel free to substitute the chicken stock for vegetable stock.You can exchange the heavy cream for half and half, but you will lose some fat and flavor.The white wine I use is almost always chardonnay, but you can use sauvignon blanc or pinto grigio.If for some reason your soup does not thicken add in a mixture of 3 tablespoons of cornstarch whisked with 6 tablespoons of cold water to make a slurry. Pour this mixture after the soup has been boiling for a few minutes and is not thickening.