For the soup:
In a large saucepan or Dutch oven, melt 1/4 c. butter over medium heat. Add onion, celery and red bell pepper; cook and stir over medium heat for about 10 minutes or until tender.
Stir in flour, cooking mixture until bubbly.
Pour in chicken stock, tomatoes (with juice), salt and sugar. Cook and stir over medium heat until mixture thickens and bubbles.
Remove from heat and cool for 5 minutes.
Carefully ladle soup into blender jar. Cover with lid and press the power button. Press "Stir" and process for 30 seconds, then press "Puree" and process for 30 seconds.
Add basil and press "Pulse" until basil is desired consistency, about 15 seconds.
Serve soup topped with Parmesan Croutons and additional snipped basil, if desired.
For the croutons:
In a small bowl, combine 2 Tbsp. butter and Parmesan cheese.
Place bread cubes in medium bowl and drizzle butter mixture over top. Toss to coat the bread and place in a single layer on a baking sheet.
Bake in preheated 350°F/180°C oven for 10 minutes. Stir and bake for 5 more minutes or until bread is golden brown and toasted.