1In a large saucepan or soup pot over medium heat, melt the butter. Add the onion and celery and cook, stirring often, until softened, three-five minutes.
2Stir in flour and cook two minutes longer.
3Pour in the chicken stock, increase the heat to high, and bring to a boil, stirring constantly. Reduce the heat to medium and cook, stirring often, until slightly reduced and thickened, about 15 minutes. Pour into a sieve set over a large bowl and strain, pushing hard on the solids to extract as much flavor as possible. Return the liquid to the sauce pan or pot.
4Whisk the peanut butter and the cream into the liquid. Warm over low heat, whisking often, for about five minutes. Do not boil.