Mushroom Soup with Floating Thyme Cream

1/4 cup heavy cream
2 teaspoons fresh thyme, chopped
3 tablespoons unsalted butter
1 pounds mixed mushrooms, fresh or dried that have been rehydrated
1 large leeks, white and pale green parts only, diced
3 tablespoons all-purpose flour
3 cups chicken stock
1 teaspoons salt
freshly ground black pepper

Using electric mixer, beat cream just until soft peaks form. Fold in 1 teaspoon thyme. Cover and refrigerate at least 2 hours to blend flavors. Remove from refrigerator 1 hour before serving to come to room temperature.

In 4-quart stock pot over moderately high heat, heat 2 tablespoons butter until hot but not smoking. cook mushrooms, stirring occasionally, until lightly browned, about 8 minutes. Transfer to large bowl.

In same stock pot over moderate heat, heat remaining 1tablespoon butter. Stir in leeks, cover, and cook, stirring often, until soft, about 5 minutes. Add cooked mushrooms, sprinkle with flour, and stir until flour is evenly distributed. Stir in stock, then salt, pepper, and remaining 1 teaspoon thyme. Bring to boil, stirring often, then reduce heat to low, set lid ajar, and simmer 20 minutes.

Divide soup among 4 bowls and float a dollop of thyme cream on top. Serve immediately.