*Vegetables above can be substituted with 5 cups frozen vegetables
Preheat oven to 350°F.
Heat oil in large heavy skillet over medium-high heat. Add garlic and stir until fragrant and lightly colored, about 30 seconds. Add pepper, zucchini, yellow squash and onion and cook, stirring, until crisp-tender, about 8 minutes.
Sprinkle with cumin and continue stirring until vegetables are tender but not soggy, about 2 minutes longer. Season generously with salt and pepper and set aside.
Place beans in large bowl; mash into coarse puree with fork. Stir in cheese and reserved vegetables.
Place tortillas on work surface. Spoon one fourth of vegetable filling down center of each, then top with one fourth of chicken and sprinkle with one fourth of cilantro.
Roll tortillas up around filling. Arrange seam-side-down on baking sheet. Cover loosely with piece of foil.
Bake for 10 minutes, or until filling is just heated through. To serve, cut each burrito into two or three sections.