Add finely minced shallots and cook until soft and translucent, about 2 to 3 minutes.
Do not brown the shallots. You want sweetness, not caramelization.
Add the Wine
Pour in the white wine and simmer until reduced by about half.
Add the Stock
Stir in the chicken stock and continue simmering for several minutes until slightly reduced. The sauce should start to look slightly glossy before the cream is added.
Add the Cream
Lower the heat and stir in the heavy cream. Simmer gently until the sauce thickens enough to lightly coat a spoon.
Avoid boiling. Gentle heat keeps the sauce smooth and silky.
Finish with Tarragon
Stir in chopped fresh tarragon and season with salt and pepper. Add part of the tarragon at the end for the freshest flavor.
Serve Immediately
Spoon the sauce over chicken, fish, pork, or vegetables while hot.