How to Make It
In a small saucepan, combine the prepeeled garlic cloves with the milk and bring to a simmer. Cook over moderately low heat until the garlic is soft and the milk has reduced to 1 cup, about 40 minutes. Transfer the mixture to a blender and puree it until smooth.
Meanwhile, in a large soup pot, combine the chicken stock, squash and sofrito and bring to a boil. Cover and cook over moderate heat until the squash is just tender, about 20 minutes. Add the shredded chicken and its juices, the peas and the creamy garlic puree. Season with salt and pepper. Simmer the chowder for 5 minutes longer and serve.
Sofrito is available in tubs in the freezer section of many supermarkets.