In a large saucepan, heat the butter and oil over medium heat. Add the chicken and brown lightly, about 6-7 minutes on each side. Once the chicken breasts are cooked (the juices should run clear) remove them from the pan and set aside.
Add the shallots, garlic, chicken base, and water to the pan. Simmer for 3 minutes. Add the raspberry preserves, vinegar, and seasonings.
Bring all to a boil and simmer, stirring, until the mixture thickens. Stir in the cream and return the chicken to the pan.
Heat the chicken for one minute to warm it, turning the pieces to coat them with the sauce.
Next time I think I'll add a few more shallots and maybe some more cream.