Cook spaghetti as indicated on package. Grill bell pepper on stove top until tender; then cut and remove seeds.
In a blender add sour cream, the cube of Knorr Base Chicken Select Soup, and the bell pepper (you may add some of the water used to cook the pasta to liquefy the sauce). Blend until it is nice and smooth.
Place the noodles on your serving dish and add sauce on top of noodles.