Puree bananas in blender (1 cup). In med. Bowl, beat pureed bananas, eggs, sugar, butter and vanilla until well blended. In large bowl, combine flour, baking powder, cinnamon and salt. Stir in choc. Chips and nuts. Make well in center of dry ingredients. Pour in banana mixture. Mix until just blended. Spoon into well-greased 2 1/2-inch muffin cups. Bake in 350 deg. Oven 25 to 30 minutes. Remove from pan. Makes about 12 muffins.