1.Heat oven to 350°F. Lightly coat baking sheet with cooking spray.
2.In large bowl, combine beans, tomatoes, chopped bell pepper, 1 clove garlic, the green onions, cilantro, hot sauce, 1/4 teaspoon cumin, juice of 1 lime, salt and black pepper; mix well. Cover; refrigerate until serving time.
3.In food processor bowl, combine SPAM® Classic, remaining 4 cloves garlic, the onion, roasted peppers, mayonnaise, remaining 1 teaspoon lime juice and 1 teaspoon cumin and the chili powder; process until smooth.
4.Slice polenta into 1/2-inch rounds; place on baking sheet. Bake 15 to 20 minutes or until golden brown and slightly crisp.
5.Remove polenta from oven; top with about 1 tablespoon SPAM® mixture.
6.Adjust oven to broil. Sprinkle polenta with cheese. Broil 2 minutes or until golden brown and cheese is melted. Serve polenta hot with black bean salsa.