Stir together first 5 ingredients and 1 cup Monterey Jack cheese; set aside.
Mash beans with a potato masher or fork in a large bowl; stir in pasta sauce and cumin. Spread one-third of bean mixture on bottom of a lightly greased 13- x 9-inch baking dish.
Layer with 3 noodles, half of spinach mixture, and 1 cup Monterey Jack cheese; repeat layers. Spread with one-third bean mixture; top with remaining 3 noodles and remaining bean mixture.
Bake, covered, at 350° for 1 hour; uncover and top with remaining Monterey Jack cheese. Bake 5 more minutes or until cheese melts. Garnish, if desired.