In a food processor puree 1 cup steamed broccoli, garlic, and 1/4 cup chicken broth.
In a large saucepan over medium heat, melt the margarine. Add the flour, and stir until mixture thickens and starts to brown.
Slowly add remaining 1 cup chicken broth and milk, stirring often. Allow mixture to thicken, about 5 minutes. Then add the puree mixture and the remaining 1 1/2 cups steamed broccoli. Heat through, and allow to thicken for about 5 minutes. Season with salt and pepper.
You can also just puree the entire soup in the pot with a immersion blender, and allow soup to thicken.