1. To prepare patties, combine first 7 ingredients in a large bowl. Divide mixture into 4 equal portions, shaping each into a 1/2-inch-thick patty. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add patties to pan; cook 7 minutes on each side or until done.
2. Combine yogurt, mint, and 1/8 teaspoon salt. Spread 1 tablespoon chutney on bottom halves of 4 buns; top each with 1 patty, 1 tablespoon yogurt mixture, 1/4 cup spinach, and a bun top.