In a saucepan, heat broth over medium high heat. Keep warm.
In a Dutch Oven, melt the butter with 2 Tbl of the broth over high heat. Add the carrots, shallot and garlic. Cook until carrots are tender.
Gradually add flour, whisking to incorporate. Cook for 1 to 2 minutes to remove the flour taste. Stir constantly.
Stir in the cream. Incorporate the taco seasoning into the remaining broth and add to the vegetable mixture. Heat to boiling.
Add the beans and corn. Reduce heat and simmer for 5 minutes, uncovered. Stir occasionally until slightly thickened. Season with salt and pepper, to taste.
Spoon unto an ungreased oven-proof casserole dish and top with the broken tortilla chips. Add the shredded cheese and bake uncovered for about 20 minutes, or until golden.
Garnish with green onions.
This makes 4 generous portions, but the recipe can easily be doubled.