Trim the dark green leaves from the leeks (leaving the white and light green parts) and the root ends of the leeks and discard.
Split the remaining white part of the leeks in half lengthwise and wash thoroughly under running water, making sure that all dirt and debris is removed from between the sections. Slice the leek halves crosswise into very thin half rounds. You should have about 3 cups

Soften the sun-dried tomatoes in warm water. When they are soft, drain and cut in small julienne strips.

In a medium sized pot, melt the butter over medium high heat. Add the leeks and onions and cook, stirring frequently, until the onions are wilted and transparent, about 8 minutes. Add the Magic Seasoning Blend and stir well. Continue to cook until the seasoning begins to darken slightly, about 2 minutes. Add the shiitake mushrooms and the julienned sun dried tomatoes. Cook, stirring frequently, until the mushrooms begin to darken, about 4 minutes. Add 1/4 cup of the champagne and stir well, scraping the bottom of the pot to dissolve any browned bits on the bottom. Add the chicken stock. Bring to a boil and simmer over medium low heat until the flavors of the soup are married, about 20 minutes.

Add the cream, stir well and return to a boil. Simmer until the soup has reduced slightly, about 10 minutes. Gradually add the cheese, stirring constantly until all the cheese has melted and dissolved. Add the remaining champagne and stir briefly.
Remove from heat and serve.